United States v. Verestin-Cruz ( 2020 )


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  •           United States Court of Appeals
    For the First Circuit
    Nos. 16-2490, 20-1402
    UNITED STATES OF AMERICA,
    Appellee,
    v.
    CARLOS RAYMUNDÍ-HERNÁNDEZ,
    Defendant, Appellant.
    _____________________
    Nos. 17-1081, 20-1405
    UNITED STATES OF AMERICA,
    Appellee,
    v.
    ROCKY MARTÍNEZ-NEGRÓN, a/k/a Rocky,
    Defendant, Appellant.
    ____________________
    Nos. 17-1092, 20-1438
    UNITED STATES OF AMERICA,
    Appellee,
    v.
    EDGAR J. COLLAZO-RIVERA,
    Defendant, Appellant.
    ____________________
    Nos. 17-1314, 18-1076, 18-1528, 20-1385
    UNITED STATES OF AMERICA,
    Appellee,
    v.
    JOVANNI VARESTÍN-CRUZ,
    Defendant, Appellant.
    APPEALS FROM THE UNITED STATES DISTRICT COURT
    FOR THE DISTRICT OF PUERTO RICO
    [Hon. Juan M. Pérez-Giménez, U.S. District Judge]
    Before
    Thompson and Kayatta,
    Circuit Judges.
    Katherine C. Essington, for appellant Raymundí-Hernández.
    Manuel E. Moraza-Ortiz, for appellant Martínez-Negrón.
    José R. Olmo-Rodríguez, for appellant Collazo-Rivera.
    Samantha K. Drake, Assistant Federal Public Defender, with
    whom Eric Alexander Vos, Federal Public Defender, and Vivianne M.
    Marrero, Assistant Federal Public Defender, Supervisor, Appeals
    Section, were on brief, for appellant Varestín-Cruz.
    Ross B. Goldman, Criminal Division, Appellate Section, U.S.
    Department of Justice, with whom Brian A. Benczkowski, Assistant
    Attorney General, Matthew S. Miner, Deputy Assistant Attorney
    General, Rosa Emilia Rodríguez-Vélez, United States Attorney, and
    Mariana E. Bauzá-Almonte, Assistant United States Attorney, Chief,
    Appellate Section, were on brief, for appellee.
    December 29, 2020
    
    Judge Torruella heard oral argument in this matter and
    participated in the semble, but he did not participate in the
    issuance of the panel's opinion in this case. The remaining two
    panelists therefore issued the opinion pursuant to 
    28 U.S.C. § 46
    (d).
    PER CURIAM. Defendants-Appellants Carlos Raymundí-Hernández
    ("Raymundí"), Rocky Martínez-Negrón ("Martínez"), Edgar Collazo-Rivera
    ("Collazo"), and Jovanni Varestín-Cruz ("Varestín") were convicted
    by a jury after an eleven-day trial for their roles in an expansive
    drug-trafficking conspiracy.       On appeal, they assert (sometimes
    collectively, and sometimes individually) that they were deprived
    of a fair trial for a multitude of reasons. Their primary unified
    challenge is that they should be entitled to a new trial because,
    at various instances throughout the trial, the district court judge
    interjected during witness testimony in such a manner that signaled
    an anti-defense bias to the jury and caused the defendants serious
    prejudice.    Martínez and Collazo also dispute the sufficiency of
    the evidence presented to the jury to support their convictions.
    And   defendants   continue   a   long-running   argument   about   Brady
    violations.
    After careful review, we find the evidence sufficient to
    support the convictions, but the trial unfair due to repeated,
    one-sided intercessions by the trial judge.        We therefore vacate
    the convictions and remand for a new trial.
    -3-
    BACKGROUND
    I. The Conspiracy and the Charges
    This    case       stems     from      the   government's      efforts       to
    dismantle an extensive conspiracy to distribute cocaine and heroin
    in Puerto Rico and other parts of the United States between 2005
    and   2010.         The    targeted       drug       trafficking     organization        (the
    "organization") was allegedly comprised of several subsets, each
    with its own leader. José Figueroa-Agosto (a/k/a "Junior Cápsula")
    and   Elvin    Torres-Estrada             ("Torres-Estrada")         were   two     of   the
    prominent kingpins, each with his own faction. Other high-ranking
    actors     included             Junior      Cápsula's        brother,       Jorge        Luis
    Figueroa-Agosto            ("Figueroa-Agosto"),               José      Marrero-Martell
    ("Marrero-Martell"), Diego Pérez-Colón ("Pérez-Colón"), and Ismael
    Luna-Archeval ("Luna-Archeval").
    The     organization          enlisted        more     than    two        dozen
    individuals         into    its        enterprise.          The    activities      of     the
    organization included transporting drugs and money between the
    Dominican Republic and Puerto Rico (mostly by boat), storing the
    drugs and money in Puerto Rico, distributing the drugs in Puerto
    Rico,    shipping         the    drugs    to    the    continental      United      States,
    instituting price controls on the sale of the drugs, laundering
    the   proceeds       from       drug     sales,      and   providing    armed     security
    throughout these operational phases.
    -4-
    In    November   2010,     the    government     indicted      Junior
    Cápsula, Marrero-Martell, Pérez-Colón, Figueroa-Agosto, and over
    a dozen others on drug conspiracy charges in a separate criminal
    case.        See    generally      United      States    v.    Figueroa-Agosto,
    No. 10-cr-00435 (D.P.R. Nov. 15, 2010).             The ensuing cooperation
    of these four named men with law enforcement was instrumental to
    the government's investigation and dismantling of the remaining
    branches of the organization and the prosecution of Raymundí,
    Varestín, Collazo, and Martínez in particular.
    On February 9, 2011, a federal grand jury indicted four
    more of the organization's leadership, including Torres-Estrada,
    Samuel        Negrón-Hernández              ("Negrón-Hernández"),            Ángel
    Ayala-Vázquez,      and   Rafael   Santiago-Martínez,         on   one   count   of
    conspiracy    to    import    cocaine    and    heroin   from      the   Dominican
    Republic, in violation of 
    21 U.S.C. §§ 952
    (a), 963. Subsequently,
    on September 18, 2013, a federal grand jury indicted twenty-seven
    other individuals alleged to have participated in the criminal
    organization, including the defendants in this case, through a
    superseding indictment that charged them with conspiracy to import
    at least five kilograms of cocaine and one kilogram of heroin, in
    violation of 
    21 U.S.C. §§ 952
    (a), 963 (Count 1), and conspiracy to
    possess with intent to distribute the same controlled substances,
    in violation of 
    21 U.S.C. § 846
     (Count 2).                      The superseding
    -5-
    indictment also charged Collazo with conspiracy to commit both
    money laundering and international money laundering, in violation
    of 
    18 U.S.C. § 1956
    (a) & (h) (Counts 3 and 4), and included several
    forfeiture allegations.       The defendants in this appeal were the
    only ones who entered pleas of not guilty and took their cases to
    trial.
    II.    The Trial
    The defendants stood trial for eleven days, from July 8
    to July 22, 2016.
    A.    The Cooperating Witnesses
    The lion's share of the incriminating evidence that the
    government put to the jury came from three cooperating witnesses:
    Marrero-Martell, Pérez-Colón, and Figueroa-Agosto.            Some of their
    testimony    was   corroborated     by   other   witnesses,   including   law
    enforcement officers.       For the purpose of our review, we briefly
    introduce these witnesses and the pertinent portions of their
    testimony.
    1. José Marrero-Martell
    Marrero-Martell was one of the original members of the
    drug trafficking organization and a high-ranking member of Junior
    Cápsula's contingent (at times, his second-in-command).
    Marrero-Martell's       testimony      implicated     Collazo,
    Raymundí, and Varestín.        He testified that Collazo transported
    -6-
    drug money to the Dominican Republic on behalf of the organization
    in his private vessels on at least two occasions in 2009, and that
    Torres-Estrada had a Porsche, which, according to other testimony,
    had been purchased for him by Collazo with laundered money.
    Marrero-Martell also testified that Raymundí was actively involved
    in collecting, unloading, storing, and distributing drugs for the
    organization.   He placed Raymundí at meetings at the home of one
    of Torres-Estrada's men, which Varestín also attended on one
    occasion.     Marrero-Martell   testified   that   both   Varestín   and
    Raymundí provided security for Torres-Estrada and that he always
    saw them carrying weapons.   According to Marrero-Martell, Varestín
    and Raymundí were remunerated for providing security, sometimes
    with drugs.
    The organization allegedly had on its payroll a police
    officer in the Dominican Republic named Colonel Amado González
    ("Colonel González").   Marrero-Martell testified that in December
    2009 he traveled to the Dominican Republic as part of a group
    (which he claimed included Varestín) sent by Junior Cápsula and
    Torres-Estrada to murder Colonel González to ensure that he could
    not identify them if he cooperated with law enforcement.1
    1 The Government explained        that Dominican authorities
    detained the group before they could   effectuate their plan to kill
    Colonel González. According to the     Government, Colonel González
    was ultimately killed "by the order    of Junior [Cápsula]," albeit
    -7-
    The defense implemented several strategies to impeach
    Marrero-Martell.            They   first    developed      the    extent   of    his
    cooperation with the government and the benefits he received in
    return.     To receive a tangible sentencing benefit, and after
    signing a proffer letter, Marrero-Martell participated in over
    fifty meetings with law enforcement personnel and he testified in
    several trials and grand jury proceedings in drug trafficking
    cases.      Pursuant to his plea and cooperation agreements, in
    exchange    for     his     assistance,     the     government     recommended     a
    significantly       lower    sentence      (105 months'      imprisonment)      than
    Marrero-Martell would have faced given the actual quantity of drugs
    he was charged with trafficking (his guideline sentencing range
    was 210 to 262 months' imprisonment).               On August 29, 2014, he was
    sentenced to 72 months' imprisonment.
    Varestín        also   sought     to    impugn       Marrero-Martell's
    credibility by drawing out potential ulterior motives for the
    testimony Marrero-Martell provided.               One such theory was that the
    drug trafficking organization was divided into competing factions,
    namely    between    Junior    Cápsula      (with   whom   Marrero-Martell       was
    aligned) and Torres-Estrada (with whom Varestín and Raymundí were
    aligned).     Notably, Torres-Estrada had allegedly tried to kill
    on a separate occasion and by a different group.
    -8-
    Marrero-Martell. Marrero-Martell testified that at various points
    between his incarceration in 2010 and his release in February 2014,
    he was jailed in the same facility and/or unit as Junior Cápsula
    and    Pérez-Colón.         Marrero-Martell     also      testified   that     they
    communicated by cell phone when jailed in separate units of the
    same facility.    This fit into the defense's larger narrative that
    Marrero-Martell       and     the    other     cooperating      witnesses       had
    coordinated their testimony to deliver a blow to Torres-Estrada's
    faction, although Marrero-Martell denied ever being asked to lie
    or offered money to testify against Torres-Estrada's organization.
    2. Diego Pérez-Colón
    Pérez-Colón      participated      in   the    organization's      drug
    trafficking   activities       and   assumed    a   managerial    role    in   the
    transportation,       distribution,     and     accounting       side    of     its
    operations from 2005 to 2010.         According to his testimony, he was
    part   of   Junior    Cápsula's      faction.       Pérez-Colón's       testimony
    implicated all four defendants.         He testified that he worked with
    Varestín and knew him well.             He also placed Varestín on the
    December 2009 trip to kill Colonel González. Pérez-Colón described
    Varestín and Raymundí as "trigger men," who would provide an armed
    escort to Pérez-Colón when receiving and moving drugs.                    Pérez-
    Colón testified that he had worked with Raymundí since early 2009
    to receive and distribute drugs.               According to his testimony,
    -9-
    Pérez-Colón would hold Junior Cápsula's drugs and Raymundí would
    hold    Torres-Estrada's       drugs,        as     Raymundí      was    one    of    the
    high-ranking members of Torres-Estrada's outfit. Pérez-Colón also
    linked Raymundí to the weapons provided to "boat captains" for
    transport to the Dominican Republic to be used in the plan "to
    kill [Colonel] Amado González."                   Pérez-Colón testified that he
    supplied      Collazo   with   drug        money    for   transportation        to    the
    Dominican Republic at least three times.                    Finally, Pérez-Colón
    stated that Martínez was an employee of Luna-Archeval, a major
    drug distributor in Puerto Rico, and that Pérez-Colón exchanged
    drugs and money with Martínez on more than seven occasions.
    Pérez-Colón      also        testified      about        the   names     of
    individuals in his drug ledger.               Specifically, he testified that
    one of the individuals listed in the ledger was named "Bocky," who
    the ledger indicated had been supplied with five kilos of cocaine.
    On cross-examination, Pérez-Colón confirmed that "Bocky" was a
    "totally different person from [defendant] Rocky Martínez."
    As with Marrero-Martell, the defense's trial strategy
    revolved around impeaching Pérez-Colón's credibility. The defense
    drew    out    information         about     the     details      of     Pérez-Colón's
    cooperation with the government.                   Like Marrero-Martell, Pérez-
    Colón   entered    into     plea    and     cooperation     agreements         with   the
    government in the hopes that it would lead to a "reduction of [his]
    -10-
    sentence."         To     that    end,       Pérez-Colón       participated      in    many
    interviews with law enforcement personnel and testified in several
    grand jury proceedings and trials.                      Pérez-Colón stated that he
    also discussed his decision to cooperate with Junior Cápsula,
    Marrero-Martell,          and      Figueroa-Agosto             (his    co-defendants).
    Ultimately, on January 22, 2016, Pérez-Colón was sentenced to
    97 months'    imprisonment,         which         was   also    the   amount     of    time
    recommended by the government (his lowest guidelines sentencing
    range was 168 to 210 months' imprisonment).
    In     furtherance         of    this      impeachment     strategy,        the
    defendants        drew    out    testimony          that   Pérez-Colón     had    indeed
    communicated with Marrero-Martell and Junior Cápsula using illegal
    cell phones while in jail to discuss the prospect of cooperating
    with the government.            Additionally, the jury heard testimony that
    Pérez-Colón        used      weapons,         bribed       officials,     and         killed
    people -- all crimes for which he was never charged.                       The defense
    elicited testimony that Pérez-Colón belonged to Junior Cápsula's
    outfit, and that Junior Cápsula was a father figure to Pérez-Colón
    --   implying        that,       like        Marrero-Martell,         Pérez-Colón       was
    incentivized        to    lie     and        to   testify       against    members        of
    Torres-Estrada's contingent. Moreover, Torres-Estrada's employees
    had kidnapped Pérez-Colón after he was blamed for a lost quantity
    of cocaine, which Pérez-Colón admitted caused him to fear for his
    -11-
    life.   Martínez also cast doubt on Pérez-Colón's testimony by
    noting that he did not remember the identities of the people who
    lived at Martínez's house despite testifying that he conducted
    several drug transactions there.
    3. Jorge Luis Figueroa-Agosto
    Figueroa-Agosto    participated      in   the    organization's
    trafficking operations under the command of his brother, Junior
    Cápsula, from sometime in 2005 until February 2008.           During his
    tenure, Figueroa-Agosto was in charge of holding and accounting
    for the proceeds from drug sales and storing drugs in Puerto Rico,
    as well as sending the money back to the Dominican Republic.
    Figueroa-Agosto directly implicated Martínez.          He testified that,
    upon arrival in Puerto Rico, portions of cocaine shipments were
    delivered to Martínez's boss, Luna-Archeval, and that Martínez
    would pick up the cocaine and store it in his house.
    Figueroa-Agosto explained that he quit the business when
    he began fearing that other members of the organization, including
    Torres-Estrada, were going to rob him or kill him.         Like Marrero-
    Martell and Pérez-Colón, Figueroa-Agosto entered into plea and
    cooperation   agreements   with   the    government.      Figueroa-Agosto
    testified that he initially suggested the idea of cooperation to
    his brother, which the defense latched onto on cross-examination
    in furtherance of their theory that the cooperating witnesses'
    -12-
    testimony was not credible. Figueroa-Agosto expected a sentencing
    reduction in exchange for his testimony in this case.             Figueroa-
    Agosto was ultimately sentenced in August 2016, about four years
    after he first entered into the cooperation agreement and one month
    after he testified at trial in this action.           At sentencing, his
    Guidelines range was 188 to 235 months' imprisonment and the
    government recommended a sentence of 107 months' imprisonment.
    The   district   court   made    a   downward   departure   and   sentenced
    Figueroa-Agosto to 87 months' imprisonment.
    B. The Key Defense Witnesses
    The defense called several witnesses of its own, some of
    whom we introduce briefly.           To illustrate its theory that the
    cooperating witnesses were incentivized to lie, Varestín called
    Jayson Dávila-Reyes ("Dávila-Reyes"), who testified that Pérez-
    Colón approached him in prison and offered him money in exchange
    for information against Torres-Estrada or any members of his
    organization.    David Rivera-Rivera ("Rivera-Rivera") was another
    key defense witness, who Varestín put on the stand to testify that,
    among other things, the December 2009 trip to the Dominican
    Republican was actually just a vacation, not a planned attempt to
    murder Colonel González.        The defense also sought to call two law
    enforcement officers who interviewed the cooperating witnesses on
    several   occasions    --   Homeland    Security   Investigation   ("HSI")
    -13-
    Special Agent Carrasquillo ("Agent Carrasquillo") and FBI Special
    Agent Mario Rentería ("Agent Rentería") -- to establish that the
    witnesses had added new details to their stories and were therefore
    unreliable.          However, the district court only permitted Agent
    Rentería to testify.
    C. The Jury Verdict
    On July 22, 2016, the jury found the defendants guilty
    of various offenses.            As to the charge of conspiracy to import
    controlled         substances    in   violation   of   
    21 U.S.C. §§ 952
    ,   963
    (Count 1), the jury convicted Raymundí but acquitted the remaining
    three defendants.        As to the charge of conspiracy to possess with
    intent to distribute controlled substances in violation of 
    21 U.S.C. § 846
     (Count 2), the jury convicted all four defendants.
    Additionally, the jury found Collazo guilty of conspiracy to commit
    both       money   laundering    and   international    money   laundering   in
    violation of 
    18 U.S.C. § 1956
     (Counts 3 and 4).
    III. The Post-Trial Motions
    Soon after the verdict, the defendants filed assorted
    motions under Rules 29 and 33 of the Federal Rules of Criminal
    Procedure, seeking judgments of acquittal or, in the alternative,
    a new trial.2         In their Rule 29 motions, the defendants asserted
    2
    Collazo sought only a judgment of acquittal under Rule 29.
    Martínez, Raymundí, and Varestín sought judgments of acquittal or,
    -14-
    that the evidence put to the jury was insufficient to sustain their
    convictions.    Their Rule 33 motions submitted that various errors
    had occurred before and during trial, which required the district
    court to grant a new trial in the interest of fairness.                     Many of
    the   grounds   they     offered     for    retrial        were      recycled     from
    contemporaneous objections made during trial.                   On May 23, 2017,
    the district court entered an omnibus order denying the defendants'
    motions across the board. The case then proceeded to sentencing.
    IV. Sentencing and Appeals
    Raymundí was sentenced to 180 months' imprisonment on
    November 18,    2016.      Martínez    and       Collazo      were     sentenced    to
    120 months'     and     97 months'     imprisonment,           respectively,        on
    December 22,    2016.       Varestín       was    sentenced       to    235 months'
    imprisonment    on    March 14,    2017.         All   four   defendants        timely
    appealed.
    DISCUSSION
    On appeal, Martínez and Collazo once again assert that
    the evidence put to the jury was insufficient to sustain their
    convictions.      Additionally,      the    defendants        allege     (sometimes
    together, sometimes separately) a kaleidoscope of errors leading
    up to and during their trial, including faulty voir dire, an
    in the alternative, a new trial, under Rules 29 and 33.
    -15-
    improperly    quashed   witness         subpoena,    judicial     misconduct,
    prosecutorial   misconduct,       and     the   wrongful      suppression   of
    impeachment   evidence. 3   The    defendants       contend   that   they   are
    entitled to a new trial -- and, in Varestín's case, if not a new
    trial, at least a new sentence.          We first address the sufficiency
    of the evidence challenges, followed by the defendants' arguments
    3 A quick note on adoption of arguments.       In his opening
    brief, Collazo "adopt[s] by reference and join[s] in the arguments
    made by [his] codefendant[s] . . . in their respective appeal
    briefs which may also be relevant to [him], particularly about the
    Brady and Giglio violations, jury selection error, exclusion of
    the testimony of agent Carrasquillo, and the various requests for
    mistrial." Martínez, for his part, filed a motion to join and
    adopt all of Varestín's appellate arguments that may be applicable
    to him.    "[I]n a case involving more than one appellant or
    appellee, including consolidated cases, any number of appellants
    or appellees may join in a brief, and any party may adopt by
    reference a part of another's brief." Fed. R. App. P. 28(i). Of
    course, the caveat is that the adopted arguments must be "readily
    transferrable from the proponent's case to the adopter's
    case." United States v. David, 
    940 F.2d 722
    , 737 (1st Cir. 1991).
    Given the nature of this case, in which the defendants stood trial
    together for crimes relating to the same drug conspiracy, and where
    the principal evidence against them derived from the testimony of
    the same cooperating witnesses, their fair trial arguments are for
    the most part readily transferable. See United States v. Ayala-
    Vázquez, 
    751 F.3d 1
    , 19 (1st Cir. 2014) (finding adoption of a co-
    defendant's judicial misconduct claims proper where both
    defendants were tried for their involvement in the same drug
    conspiracy).
    -16-
    about judicial interventions, and lastly their contentions about
    Brady and Giglio errors.
    I. Sufficiency of the Evidence
    Our first step is to address whether the government
    adduced evidence sufficient to sustain Martínez and Collazo's
    convictions (they are the only two defendants who assert this
    challenge   on   appeal).     We    proceed   in    this   order   because   "a
    successful sufficiency challenge" would both require us to vacate
    their convictions and bar retrial for the same offenses under the
    Double Jeopardy Clause of the Fifth Amendment (thus also rendering
    moot their remaining claims of trial error).                United States v.
    Ramírez-Rivera, 
    800 F.3d 1
    , 16 (1st Cir. 2015), abrogated on other
    grounds by United States v. Leoner-Aguirre, 
    939 F.3d 310
    , 317 (1st
    Cir. 2019).
    As   to   Martínez,    the   district   court    found   that    the
    evidence supported the conclusion that Martínez was involved in
    aspects of the drug inventory, including storage and distribution.
    As to Collazo, the district court found that the evidence supported
    the conclusion that he delivered millions of dollars in drug money
    to the Dominican Republic using his boat, that he purchased a car
    for a leader of the drug cartel using illicit funds, and that he
    intended to join in the drug trafficking conspiracy.
    -17-
    We review de novo the denial of a Rule 29 motion for
    judgment of acquittal based on insufficient evidence.           See United
    States v. Troy, 
    583 F.3d 20
    , 24 (1st Cir. 2009).           In our review,
    "[w]e consider all the direct and circumstantial evidence in the
    light most flattering to the government, 'drawing all reasonable
    inferences consistent with the verdict, and avoiding credibility
    judgments, to determine whether a rational jury could have found
    the   defendants      guilty     beyond       a   reasonable      doubt.'"
    Ramírez-Rivera,    800   F.3d   at    16    (quoting   United   States   v.
    Negrón-Sostre, 
    790 F.3d 295
    , 307 (1st Cir. 2015)).                While a
    sufficiency challenge is a "formidable" task for the movant and an
    "uphill battle," United States v. Rivera-Rodríguez, 
    617 F.3d 581
    ,
    596 (1st Cir. 2010) (quoting United States v. Lipscomb, 
    539 F.3d 32
    , 40 (1st Cir. 2008)), it is in no way an "empty ritual," 
    id.
    (quoting United States v. de la Cruz-Paulino, 
    61 F.3d 986
    , 999
    n.11 (1st Cir. 1995)); see also United States v. Brandao, 
    539 F.3d 44
    , 50 (1st Cir. 2008) ("[W]e will reverse only if the verdict is
    irrational.").
    A. Martínez's Sufficiency Challenge
    Martínez contends that his conviction for conspiracy to
    possess with the intent to distribute controlled substances in
    violation of 
    21 U.S.C. § 846
     (Count 2) should be overturned because
    the evidence was insufficient to establish that he knew the boxes
    -18-
    he handled contained drugs (as opposed to some other item or
    contraband),    and   therefore   he    could   not     have    knowingly    or
    voluntarily joined the drug distribution conspiracy.
    Count 2   alleged   the    existence   of    a     wholesale    drug
    distribution conspiracy, as part of which, the defendants "would
    store and protect the narcotics and narcotics proceeds within
    Puerto Rico," and that "some of the narcotics would be divided
    among the coconspirators for further distribution."                 Thus, the
    relevant question for Martínez's sufficiency challenge is "whether
    a reasonable jury could conclude that the [g]overnment proved
    beyond a reasonable doubt each element of the crime:                   (1) 'a
    conspiracy existed,' (2) [the defendant] 'had knowledge of the
    conspiracy' and (3) [he] 'knowingly and voluntarily participated
    in the conspiracy.'" United States v. Burgos, 
    703 F.3d 1
    , 10 (1st
    Cir. 2012) (quoting United States v. Dellosantos, 
    649 F.3d 109
    ,
    116 (1st Cir. 2011)).      On appeal, Martínez only challenges the
    second and third elements.
    To satisfy the second element, the government must prove
    "knowledge of the crime charged," 
    id.,
     either in the form of
    "actual knowledge" or "willful blindness," id. at 11 (citation
    omitted).   It is insufficient to "[s]how[] that the defendant had
    knowledge of generalized illegality," id. (citing United States v.
    Pérez-Meléndez, 
    599 F.3d 31
    , 43 (1st Cir. 2010)), though the
    -19-
    government need only establish knowledge that "the conspiracy
    involved a controlled substance" and not necessarily knowledge of
    the "specific controlled substance being distributed," id.; cf.
    McFadden v. United States, 
    576 U.S. 186
    , 188-89 (2015) (holding
    that a conviction under 
    21 U.S.C. § 841
    (a)(1) requires knowledge
    that the defendant is "dealing with 'a controlled substance'" as
    opposed to "an illegal or regulated substance under some law" in
    a case involving bath salts, a controlled substance analogue).
    "[C]harges of conspiracy cannot be made out by piling inference
    upon inference."          Burgos, 703 F.3d at 11 (citing United States v.
    DeLutis, 
    722 F.2d 902
    , 907 (1st Cir. 1983)).
    To satisfy the third element, the government must prove
    that    "the    defendant         both    intended     to   join   the   conspiracy
    and intended to effectuate the objects of the conspiracy."                        
    Id.
    (quoting Dellosantos, 
    649 F.3d at 116
    ).                 "An agreement to join a
    conspiracy may be express or tacit," United States v. Santos-Soto,
    
    799 F.3d 49
    ,   57    (1st    Cir.    2015)     (quoting   United   States    v.
    Trinidad-Acosta, 
    773 F.3d 298
    , 311 (1st Cir. 2014)), and viable
    evidence may include "inferences 'drawn from members' words and
    actions and from the interdependence of activities and persons
    involved,'" 
    id.
     (quoting United States v. Acosta-Colón, 
    741 F.3d 179
    , 190 (1st Cir. 2013)).               To be sure, a defendant may be deemed
    part of a conspiracy even if he only participates in ancillary
    -20-
    functions, such as communications, accounting, or enforcement, as
    opposed to more central functions like collecting, handling, or
    selling drugs. See 
    id. at 58
    .
    The   gist   of   Martínez's    alleged    involvement   in    the
    organization      is   that   he   worked   for    Luna-Archeval,    a    drug
    distributor who also happened to be in the car parts and mechanic
    business.    According to witness testimony, on behalf of Luna-
    Archeval, Martínez accepted and stored boxes containing drugs at
    the auto shop and his own home.         Martínez, for his part, asserts
    that there is insufficient evidence to show that he knew the boxes
    he handled contained drugs.        Specifically, he contends that absent
    any showing that the boxes were opened in his presence or that any
    of the witnesses told him that the boxes contained drugs, it was
    reasonable for him to infer that those boxes contained auto parts
    (perhaps even stolen auto parts or something else illegal), given
    the nature of his employment for Luna-Archeval and the fact that
    auto parts were regularly delivered in boxes to the auto shop. As
    a result, Martínez maintains, there is insufficient evidence to
    establish that he was part of the conspiracy.
    We    find   these     arguments      unpersuasive.      Witness
    credibility aside, the government presented sufficient evidence at
    trial that would allow a reasonable jury to conclude beyond a
    reasonable doubt that Martínez knew that the boxes he handled
    -21-
    contained drugs (i.e., that he knew the conspiracy existed) and
    that he knowingly and voluntarily participated in the conspiracy.
    Pérez-Colón and an FBI agent testified that Martínez
    worked for Luna-Archeval, who was "one of the biggest distributors"
    in   the   drug   trafficking    conspiracy,   and   to   whom   Pérez-Colón
    supplied drug shipments.        Pérez-Colón explained that he delivered
    boxes containing drugs to Martínez, who received them for Luna-
    Archeval, in exchange for money.        The organization's distributors
    delivered "things" (i.e., drugs and/or money) to Luna-Archeval in
    boxes because it made sense within the context of Luna-Archeval's
    business, which received boxes of auto parts.             Pérez-Colón also
    testified that when he ran out of drugs to distribute, he sometimes
    picked up a new supply of drugs from Martínez's house -- usually
    cocaine but sometimes heroin.       When asked how Martínez "knew that
    he was dealing with drugs," Pérez-Colón explained, "[b]ecause when
    I ran out of kilos, I would tell [Figueroa-Agosto], and [Figueroa-
    Agosto] would call [Luna-Archeval], and then [Luna-Archeval] would
    call me and tell me to go to his employee's house [i.e., Martínez's
    house] to pick up the kilos."          Pérez-Colón also testified that
    when he went to Martínez's house, Martínez "would take the kilos
    out and give them to me.         They were cocaine kilos, and once or
    [on] three occasions there were heroin kilos."               Occasionally,
    Pérez-Colón would give Martínez drug money that "was counted, all
    -22-
    organized, all nice, and it was all tallied up."                All in all,
    Pérez-Colón testified that he dealt with Martínez upward of seven
    times and that on some of those occasions, they would exchange a
    "full tally" of drugs in the range of hundreds of kilos.
    All in all, if a rational jury believed this testimony,
    it could easily find that Martínez knew that the boxes he received,
    stored, and exchanged for money contained drugs.             The jury could
    also reasonably conclude based on this evidence that Martínez had
    a   stake   in   the   conspiracy    based     on   his   relationship     with
    Luna-Archeval. See United States v. Azubike, 
    564 F.3d 59
    , 65 (1st
    Cir. 2009) (Azubike II) ("[D]rug organizations do not usually take
    unnecessary risks by trusting critical transactions to outsiders."
    (quoting United States v. Azubike, 
    504 F.3d 30
    , 37 (1st Cir. 2007)
    (Azubike I))).     While the evidence may not suggest that Martínez
    played a leading role in the conspiracy, collecting, storing, and
    selling drugs are core functions of a drug distribution conspiracy.
    See Santos-Soto, 799 F.3d at 58. Furthermore, there is sufficient
    evidence for the jury to conclude beyond a reasonable doubt that
    he knew his service advanced the principle aims of the conspiracy.
    See id.
    B. Collazo's Sufficiency Challenge
    We   now   turn   to   Collazo's   challenge    that   there    was
    insufficient evidence to sustain his convictions for conspiracy to
    -23-
    possess with intent to distribute controlled substances (Count 2),
    conspiracy to commit concealment money laundering (Count 3), and
    conspiracy to commit international money laundering (Count 4).
    1. Drug Distribution Conspiracy Conviction
    As to Count 2, Collazo stood accused of conspiring to
    transport millions of dollars of drug money to and from the leaders
    of the organization.   He disputes the sufficiency of the evidence
    undergirding his § 846 conviction on the grounds that it was based
    entirely on Pérez-Colón and Marrero-Martell's testimony, which was
    vague, contradictory, and uncorroborated. We disagree.
    Marrero-Martell recalled three particular instances of
    Collazo's involvement with the organization:   first, in May 2009,
    Collazo transported between $1.5 and $2.5 million from Puerto Rico
    to the Dominican Republic in a forty-foot private fishing vessel
    for which he was paid a commission; second, in either June or July
    2009, Marrero-Martell saw Collazo and others at Torres-Estrada's
    home in the Dominican Republic where they had dinner; and third,
    in September 2009, Collazo transported upwards of $1 million to
    the Dominican Republic shortly after an assassination attempt on
    Junior Cápsula during which corrupt Dominican authorities stole
    the kingpin's drug money.   The money was in cash and transferred
    in ziplock bags and plastic bins, which further suggests its
    illicit nature.    Marrero-Martell indicated that approximately
    -24-
    $900,000 of the money that Collazo delivered in September 2009 was
    likely intended to pay Junior Cápsula's girlfriend's bond in the
    Dominican Republic.     According to Marrero-Martell, Collazo also
    transported Negrón-Hernández back to Puerto Rico on the return
    trip.    Marrero-Martell testified that, as was custom, Collazo
    received an up-front commission (typically eight or ten percent)
    for this trip as well.
    Pérez-Colón testified that he dealt with Collazo at
    least three times.      After the assassination attempt on Junior
    Cápsula, Pérez-Colón stated that Marrero-Martell escorted him to
    Collazo's place of business.        Pérez-Colón delivered approximately
    $3 million for Collazo to transport to Junior Cápsula in the
    Dominican Republic "to solve a lot of things that were happening"
    (including paying his girlfriend's bond) in the wake of the attempt
    on Junior Cápsula's life, during which he lost "all of his" drug
    money.   Pérez-Colón stated that the money he delivered to Collazo
    was "drug proceeds" and that he did not pay Collazo or know how
    much Collazo would be paid for his services.           Pérez-Colón also
    testified that, on another occasion, he gave Collazo roughly
    $2 million    for   delivery   to    Torres-Estrada   in   the   Dominican
    Republic.     Pérez-Colón always showed Collazo the money before
    transferring it to Collazo's possession.         Pérez-Colón suspected
    that the reason the organization conscripted Collazo was because
    -25-
    "he had a good vessel and . . . a good last name," and that it
    would make a difference if the authorities stopped "Empresas
    Collazo"    (Collazo's     enterprises)        as    opposed   to   "Diego     Pérez-
    Colón."
    Count 2 alleged that it was "a manner and means of the
    conspiracy that the defendants and their co-conspirators would
    send   bulk    shipments    of      narcotics       proceeds   to   the     Dominican
    Republic," and that they "conceal[ed] and hid[] . . . [the] acts
    done   in     furtherance      of    the   conspiracy."             Based    on     the
    aforementioned testimony, a rational jury could certainly infer
    that   Collazo    knew   the     drug   conspiracy       existed,     and    that    he
    voluntarily participated in its activities for personal financial
    gain by transporting drug proceeds to the Dominican Republic in
    furtherance of the organization's broader objectives.                       From the
    quantity of cash that Collazo allegedly delivered, the number of
    the trips he allegedly made, and his extensive interactions with
    members of the drug trafficking organization, the jury could also
    reasonably infer that Collazo had actual knowledge of the charged
    conspiracy.     Collazo does not seem to dispute that he transported
    some cash to the Dominican Republic at the request of certain
    members of the organization, but he contends that it was earmarked
    for paying the bond of Junior Cápsula's girlfriend.                   But based on
    the modus operandi of the organization -- buying drugs in the
    -26-
    Dominican Republic and shipping them to Puerto Rico -- the jury
    also could have reasonably inferred that at least some of the money
    Collazo delivered was used in furtherance of the conspiracy's drug
    trafficking aims, regardless of whether Collazo ferried drugs back
    to Puerto Rico himself.       After all, drug trafficking organizations
    do not typically entrust millions of dollars in proceeds from drug
    sales to a clueless "outsider." See Azubike II, 
    564 F.3d at 65
    .
    Collazo focuses much of his argument on highlighting
    three     discrepancies      in   Marrero-Martell       and     Pérez-Colón's
    testimony,    which    he   submits   incurably    undermine    the   evidence
    against him:     first, that Marrero-Martell and Pérez-Colón do not
    agree as to whether Collazo was paid for the September 2009 trip;
    second, while Marrero-Martell recalls that Collazo transported a
    money shipment to the Dominican Republic in May 2009, Pérez-Colón
    recalls    Collazo's    involvement     in   a    shipment    sometime   after
    September 2009; and third, that while Marrero-Martell recalled
    Collazo's fishing boat to be forty-feet long, HSI Agent Ricardo
    Mayoral ("Agent Mayoral") testified that Collazo's vessel was
    approximately sixty-one feet long.
    While the defendants certainly could argue that these
    inconsistences undercut the witnesses' testimony, the jury was not
    required to so find. As we have held, "[e]vidence does not become
    legally insufficient merely because of some inconsistencies in
    -27-
    witnesses' testimony." United States v. Ayala-García, 
    574 F.3d 5
    ,
    12 (1st Cir. 2009) (quoting United States v. Rodríguez, 
    457 F.3d 109
    , 119 (1st Cir. 2006)).   Further, Agent Mayoral testified that
    he detained a boat with Collazo and others (including Negrón-
    Hernández) for a border search in September 2009, when the men
    were on their way back from the Dominican Republic. While some of
    the men explained that they had been fishing, no fish or fishing
    equipment was found on the boat. The jury thus at least had enough
    corroboration to reasonably infer Collazo's knowing participation
    in the September 2009 shipment beyond a reasonable doubt.
    Accordingly, on balance, there is sufficient evidence to
    sustain Collazo's § 846 conviction.
    2. Money Laundering Convictions
    Next, Collazo argues that Counts 3 and 4 should be
    overturned because there is insufficient evidence to establish
    that he knew that the money he used to purchase a luxury car or
    the money he transported to the Dominican Republic derived from
    unlawful activity. Again, we disagree.
    First, to affirm a conviction for conspiracy to commit
    concealment money laundering under 
    18 U.S.C. § 1956
    (h), we must
    find that the government presented sufficient evidence for a
    reasonable jury to find beyond a reasonable doubt that Collazo
    (1) "knowing that the property involved in a financial transaction
    -28-
    represents    the    proceeds     of   some    form    of    unlawful   activity,"
    (2) conspired "to conduct such a financial transaction which in
    fact   involves      the   proceeds    of     specified      unlawful   activity,"
    (3) with "know[ledge] that the transaction is designed in whole or
    in part . . . to conceal or disguise the nature, the location, the
    source, the ownership, or the control of the proceeds of specified
    unlawful activity."        United States v. Ayala-Vázquez, 
    751 F.3d 1
    ,
    14-15 (1st Cir. 2014) (alteration in original) (quoting United
    States v. Cedeño-Perez, 
    579 F.3d 54
    , 57 (1st Cir. 2009)).
    The "specified unlawful activity" alleged in Count 3 was
    "the     felonious    importation,      receiving,          concealment,      buying,
    selling, or otherwise dealing in controlled substances."                      Count 3
    specifically alleged that Collazo was part of the organization's
    conspiracy "to conceal and disguise drug trafficking proceeds" by
    arranging for "bulk shipments" of drug proceeds to the Dominican
    Republic in "privately owned yachts," depositing drug money in
    "nominee bank accounts," paying for goods with checks from those
    accounts    to   conceal    the   ownership      and    source    of    the    money,
    commingling drug money with legitimate business proceeds, and
    buying goods while misrepresenting the source of the money used to
    pay for them.
    On balance, Collazo's sufficiency challenge is without
    merit.    In addition to the aforementioned evidence about Collazo's
    -29-
    transportation of millions of dollars in drug proceeds for the
    organization, there was testimony that, in 2008, Collazo purchased
    a "very rare" Porsche GT2 for $313,699 in a cash deal.        Collazo's
    taxable income in 2008 was $12,038, which suggests that the lavish
    car payment was part of a money-laundering scheme.            There was
    testimony   that   Collazo   had   several   companies,   including   ECR
    Transport, Transporte Collazo, and Empresas Collazo.        The license
    and title for the car were registered to ECR Property, which the
    jury could reasonably infer was also an entity belonging to
    Collazo. According to the president of the car dealership, Victor
    Gómez, Collazo paid for the car with a mix of cash and checks from
    different corporate entities.      This included two $100,000 checks
    drawn from the account of AC Electroamerica, an entity that the
    organization used to launder drug proceeds by purchasing luxury
    items such as cars and boats.
    Marrero-Martell testified that it was common practice
    for high-ranking members of the drug trafficking organization,
    like himself and Torres-Estrada, to put such goods under the names
    of third parties.    Cf. United States v. Martínez-Medina, 
    279 F.3d 105
    , 116 (1st Cir. 2002) ("Purchasing large items with drug money
    through third parties surely supports an inference of intent to
    conceal.").   Most of Torres-Estrada's "things were not under his
    name." Moreover, Marrero-Martell testified that only four or five
    -30-
    Electroamerica checks were used for such purchases, and that he
    knew    that     Torres-Estrada     bought       a   Porsche GT2         with   an
    Electroamerica check.        The president of the car dealership that
    sold Collazo the Porsche GT2 testified that the company only
    imported one or two of them that year.               He also testified that
    Collazo did not take delivery of the Porsche GT2.                 The jury could
    reasonably infer from this evidence that Collazo knew that he was
    using drug money to buy the Porsche GT2 in service of obscuring
    the paper trail for a leader of the drug trafficking organization.
    Cf. Ayala-Vázquez, 751 F.3d at 15–16 (affirming conviction for
    conspiracy to commit money laundering "through the acquisition of
    various   vehicles,"    including       luxury   cars,    where    the   evidence
    showed that the defendant "used a 'straw purchaser' to buy and
    register the[] vehicles in order to conceal the fact that they
    were bought and paid for with drug money").                Here, the evidence
    gives rise to the reasonable inference that Collazo was the "straw
    purchaser."
    Moreover, the government adduced testimony that Collazo
    added   the    Porsche GT2   to   the    commercial      insurance    policy    he
    maintained for his transportation businesses.               The evidence also
    showed that the two money orders used to pay for the Porsche GT2's
    policy in 2008 were made out by the CEO of the insurance company
    at the time, who was fishing buddies with Collazo (and who has
    -31-
    since passed).     Additionally, the CEO's secretary, Sandra Rios,
    testified that around that time, Collazo brought $15,000 in cash
    (about the value of the policy) to the CEO's offices in a "medium
    sized   brown   [paper]   bag."      This   is    textbook    concealment      in
    connection with a money laundering conspiracy.                See id. (noting
    that payments "placed in plastic or paper bags" can "demonstrate[]
    an intent to conceal (citing United States v. Cedeño-Pérez, 
    579 F.3d 54
    , 61 (1st Cir. 2009))). From this evidence, the jury could
    reasonably infer that Collazo knowingly laundered drug money by
    purchasing of the car as well as the insurance policy.
    Next, our analysis of the sufficiency of the evidence on
    Collazo's conviction for conspiracy to commit international money
    laundering in violation of § 1956(a)(2)(B)(i) and (h) differs only
    in that it also assesses whether the government has put forth
    sufficient evidence that Collazo conspired to "transport funds
    from the United States to [a foreign country]." Cuellar v. United
    States, 
    553 U.S. 550
    , 561 (2008).           Count 4 alleged that Collazo
    transported     approximately     $8 million     from   Puerto    Rico   to   the
    Dominican     Republic    in    furtherance       of    the      organization's
    objectives.
    As we have noted, there was testimony that around
    $900,000 of an alleged $2 million transported by Collazo to the
    Dominican Republic in September 2009 was earmarked to pay Junior
    -32-
    Cápsula's girlfriend's bond.      However, that does not establish, as
    Collazo urges us to find, that he lacked knowledge that the money
    he transported to the Dominican Republic derived from drug sales.
    As we concluded with respect to his § 846 challenge, a jury could
    have reasonably inferred from the whole of the evidence that
    Collazo knew that the millions of dollars he transported to the
    Dominican Republic over the course of several trips derived from
    the unlawful activity of drug trafficking.                 Therefore, we find
    that the evidence was indeed sufficient to sustain Collazo's
    conviction on Count 4 as well.
    II. Comments Made by the Trial Judge
    Out of all the issues on appeal, the defendants' primary
    unified challenge is that they should be entitled to a new trial
    because, at various crucial points throughout the trial, the
    district court judge interjected during witness testimony in such
    a manner that signaled an anti-defense bias to the jury and caused
    the defendants serious prejudice.           The defendants allege that the
    district court judge "improperly intruded into the questioning of
    witnesses, simultaneously assuming the role of the prosecutor and
    manifesting    disdain   for   the    defense['s]     theory"    and    thereby
    subverting    the   credibility      of   key   defense    witnesses.      They
    specifically call into question several aspects of the trial
    judge's   conduct     during   the        testimony   of     defense    witness
    -33-
    Dávila-Reyes.     Varestín and Collazo (plus Martínez by way of
    adoption) also protest the trial judge's interjection in the
    testimony of defense witness Rivera-Rivera.4
    A.   Legal Framework
    As part of the basic guarantees of due process, "a trial
    judge should be fair and impartial in his or her comments during
    a jury trial."     de la Cruz-Paulino, 
    61 F.3d at 997
     (citation
    omitted).   Criminal defendants bringing a judicial bias claim can
    prevail on appeal if they successfully establish that "(1) the
    court's intervention gave the appearance of bias and (2) the
    apparent bias seriously prejudiced [them]."       United States v.
    Rivera-Rodríguez, 
    761 F.3d 105
    , 112-13 (1st Cir. 2014) (referring
    to the second prong as the "serious prejudice" test); see also
    United States v. Márquez-Pérez, 
    835 F.3d 153
    , 158, 161 (1st Cir.
    4 Collazo adds a few more fish to the pond too. He flags the
    trial judge's questioning of defense witness Eliezer De Jesús, a
    coworker of Varestín and Rivera-Rivera who offered general
    testimony as to Varestín's good character, as another instance of
    misconduct. He also highlights that during his defense counsel's
    cross-examination of Agent Mayoral and his closing argument, the
    trial judge made statements that undermined the counsel's
    credibility, "basically telling the Jury that the attorney was
    making things up."     We deem these claims waived for lack of
    sufficient argumentation. See United States v. Zannino, 
    895 F.2d 1
    , 17 (1st Cir. 1990) ("[I]ssues adverted to in a perfunctory
    manner, unaccompanied by some effort at developed argumentation,
    are deemed waived."). Even if not waived, we need not reach them
    here given our ultimate disposition of the judicial misconduct
    issue in favor of the defendants.
    -34-
    2016); Ayala-Vázquez, 751 F.3d at 24.
    We review preserved claims that a trial judge's actions
    deprived a defendant of a fair trial "for abuse of discretion, the
    same standard applied to our review of the trial judge's denial of
    the motion for a mistrial."          Ayala-Vázquez, 751 F.3d at 23; see
    also United States v. Pagán-Ferrer, 
    736 F.3d 573
    , 586 (1st Cir.
    2013) ("When reviewing the denial of a motion for a mistrial, 'we
    consider the totality of the circumstances to determine whether
    the defendant has demonstrated the kind of "clear" prejudice that
    would render the court's denial of his motion for a mistrial a
    "manifest    abuse    of   discretion."'"      (quoting       United   States   v.
    Dunbar, 
    553 F.3d 48
    , 58 (1st Cir. 2009))). By contrast, we review
    unpreserved claims for plain error.                  United States v. Lanza-
    Vázquez, 
    799 F.3d 134
    , 142 (1st Cir. 2015).               Defendants carry a
    higher burden under this standard because they must demonstrate
    that "(1) an error occurred, (2) the error was obvious, (3) the
    error affected substantial rights, and (4) the error seriously
    impaired the fairness, integrity, or public reputation of judicial
    proceedings."    United States v. LaPlante, 
    714 F.3d 641
    , 643 (1st
    Cir.   2013)   (citation    and     internal    quotation      marks   omitted).
    However, we have previously noted that the serious prejudice test
    in a judicial bias claim more or less saddles criminal defendants
    with   a    similar   burden   to    the     plain    error    standard.        See
    -35-
    Rivera-Rodríguez, 761 F.3d at 112 & n.7 (noting that although the
    serious prejudice standard does not "formally incorporate" the
    fourth prong of plain error, since a serious prejudice finding
    means the judge's misconduct compromised the fairness of a trial,
    "the improper conduct necessarily affects the fairness, integrity,
    or public reputation of judicial proceedings"); see also United
    States v. Cruz-Feliciano, 
    786 F.3d 78
    , 84–85 (1st Cir. 2015)
    (reinforcing that establishing a burden of "serious prejudice" is
    "comparable to demonstrating prejudice under plain error review").
    Under certain circumstances, a judge's behavior can be
    "per se misconduct." Márquez-Pérez, 835 F.3d at 158. This happens
    when   judges   "exceed   their   authority"    by   "testify[ing]   as
    witnesses, or add[ing] to or distort[ing] the evidence."       Id.   It
    can also happen when judges "opin[e] to the jury on the credibility
    of witnesses, the character of the defendant, or the ultimate
    issue." Id. Defendants must still establish serious prejudice on
    this theory. Id.
    If the judge's actions are not per se misconduct, we
    assess whether the trial judge abused his or her discretion by
    demonstrating improper partiality in front of the jury.       Id.; see
    also Ayala-Vázquez, 751 F.3d at 23-24.         This assessment by its
    nature is very case specific. "To determine whether the jury would
    perceive bias, we often must examine each intervention in the
    -36-
    context of the trial as a whole."      Rivera-Rodríguez, 761 F.3d
    at 111.
    The trial judge plays the role of "governor of the
    trial," not "mere moderator," Quercia v. United States, 
    289 U.S. 466
    , 469 (1933), so his or her "active participation" alone "does
    not create prejudice []or deprive [a criminal defendant] of a fair
    trial," Deary v. City of Gloucester, 
    9 F.3d 191
    , 194 (1st Cir.
    1993).     To be sure, the trial judge is afforded fairly wide
    latitude to "question witnesses and to analyze, dissect, explain,
    summarize, and comment on the evidence."   Logue v. Dore, 
    103 F.3d 1040
    , 1045 (1st Cir. 1997); see also Fed. R. Evid. 614(b) ("The
    court may examine a witness regardless of who calls the witness.").
    Trial judges are given leeway to "criticize counsel, and express
    'impatience, dissatisfaction, annoyance, and even anger,'" such
    that "'a stern and short-tempered judge's ordinary efforts at
    courtroom administration' are not error." Márquez-Pérez, 835 F.3d
    at 158 (quoting Liteky v. United States, 
    510 U.S. 540
    , 555-56
    (1994)).
    But with great power comes great responsibility.   Trial
    judges cross the line of neutrality if they "misemploy [their]
    powers," 
    id.,
     by assuming "the role of an advocate or 'otherwise
    us[ing] [their] judicial powers to advantage or disadvantage a
    party unfairly,'" Ayala-Vázquez, 751 F.3d at 24 (quoting Logue,
    -37-
    
    103 F.3d at 1045
    ).       Remaining impartial in a justice system built
    on jury trials is essential to guaranteeing the due process rights
    of criminal defendants, for the jury may be swayed by a judge's
    "lightest word or intimation."           Starr v. United States, 
    153 U.S. 614
    ,   626     (1894).      Importantly,       "the   concern    with    judicial
    interrogation" is not that the court will "expose[] bad facts,
    inconsistencies,      or    weaknesses    in    the   case"     by   questioning
    witnesses. Rivera-Rodríguez, 761 F.3d at 113. What is problematic
    is "giv[ing] jurors the impression that [the court] has an opinion
    on the correct or desirable outcome of the case," including about
    the relevance or credibility of a witness, as this effectively
    usurps the jury's role. Id.
    The other half of the bias test is the serious prejudice
    inquiry.      An improper judicial intervention results in serious
    prejudice when "there is a reasonable probability that, but for
    the error, the verdict would have been different."                   Id. at 112.
    "In analyzing prejudice, our cases regularly weigh three factors:
    (1) the nature and context of the error, (2) the presence of
    curative instructions, and (3) the strength of the evidence in
    support of the judgment."         Márquez-Pérez, 835 F.3d at 161.             Of
    additional note, "in cases with multiple judicial interventions,
    determining the appearance of bias and the prejudicial effect of
    that   bias     generally    involves    a     cumulative   effect      inquiry."
    -38-
    Rivera-Rodríguez, 761 F.3d at 112.
    B. The Court's Interventions
    1. Testimony of Jayson Dávila-Reyes
    The defense's principal trial strategy was to impeach
    the    credibility          of    cooperating        witnesses     Pérez-Colón       and
    Marrero-Martell, whose testimony constituted the overwhelming bulk
    of    the       potentially      incriminating       evidence    put   to   the    jury.
    Varestín called Dávila-Reyes in service of this theory.                           At the
    time       of   his   testimony,     Dávila-Reyes       was   imprisoned     on    prior
    unrelated         gun     and    drug     charges.       Varestín      posited      that
    Dávila-Reyes's           testimony      was    especially     trustworthy    because,
    unlike the cooperating witnesses, he was not offered (nor did he
    expect) a sentencing benefit in exchange for taking the stand. Of
    particular note, Dávila-Reyes testified that, while imprisoned in
    the same unit, the government's cooperating witness Pérez-Colón
    offered him money "[t]o give false information to be used as
    testimony         against    other      people."      Specifically,     Dávila-Reyes
    stated that Pérez-Colón inquired about "whether [Dávila-Reyes]
    knew of any violent crime committed by [Torres-Estrada] and his
    gang," including Varestín. 5                  Dávila-Reyes recalled that Pérez-
    Colón implied that he would take what information Dávila-Reyes
    5
    Dávila-Reyes also testified that he knew Varestín a little
    bit and never saw him with a gun or committing a violent act.
    -39-
    could provide and "bulk it up."
    Dávila-Reyes explained that Pérez-Colón "wanted to get
    information"      because      "[a]pparently,          he    was   really   upset    at
    [Torres-Estrada]."         Dávila-Reyes recalled that Pérez-Colón said
    something to the effect that "he wanted to hit [Torres-Estrada]
    with everything he had," meaning "[his people] were going to be
    really in trouble."          Dávila-Reyes also explained that Pérez-Colón
    likely approached him in the first place because "[b]ack then
    [Dávila-Reyes]         was        having      [his          own]     problems       with
    [Torres-Estrada]."           Dávila-Reyes understood that Pérez-Colón's
    offer was coming from Junior Cápsula.                   In the end, Dávila-Reyes
    did not accept the offer.
    On cross-examination, the government sought to discredit
    Dávila-Reyes's plainly relevant attack on the government's case by
    questioning Dávila-Reyes about his criminal history. In so doing,
    the government wandered fairly far afield, asking about the origins
    of   his   drug   supply     in    relation       to   his   prior   drug   offenses.
    Raymundí objected to this line of questioning twice, which the
    district court denied both times.                 Then, Varestín also lodged an
    objection leading to the following interaction with the court
    before the jury:
    VARESTÍN:          Objection, Your Honor. First of all,
    beyond scope.    Second of all, the
    government is eliciting information
    that is not relevant to this trial,
    -40-
    Your Honor.
    THE COURT:      His testimony also is not relevant in
    this case.
    VARESTÍN:       Well,   Your   Honor,   we   differ,
    obviously,   but   I   believe   his
    testimony is relevant.
    THE COURT:      Counsel, he's accepted that he dealt
    in drugs. The question is, where did
    you get the drugs? If he says it was
    his own drugs, does that mean he grew
    them up in his back yard, or where
    did he get the drugs? That's the only
    question.
    The     government   then     proceeded   to   engage     with
    Dávila-Reyes's response that his indictment for his role in a drug
    conspiracy charged him as "an enforcer," not "a runner." When the
    government asked Dávila-Reyes to explain what "the enforcer does
    for the conspiracy," Raymundí and Varestín both lodged objections
    based on scope and relevance.         The court rebuffed Raymundí's
    attempt to object, noting that Dávila-Reyes was not his witness,
    and   overruled   Varestín's   objection.      Subsequently,   as   the
    government exhausted its attack on Dávila-Reyes, the court took
    over questioning the witness about the nature of his role as an
    "enforcer":
    THE COURT:       What would happen if somebody tried
    to take away the drugs or tried to
    interfere with the drug point of the
    people that you are protecting? What
    would you do? I am not saying about
    at that time.
    -41-
    DÁVILA-REYES:   Back then, I am not going to lie to
    you but --
    THE COURT:      What would you do as an enforcer?
    DÁVILA-REYES:   Protect the drugs.
    THE COURT:      How would you do that?
    DÁVILA-REYES:   I would use all the means I have
    available. That's why I am paying 14
    years, Your Honor. That’s why I am
    paying 14 years.
    THE COURT:      I am not asking you that.       I am
    asking you, what would you do in such
    circumstances?
    DÁVILA-REYES:   Protect the drugs, sir.
    THE COURT:      What would you do to protect the
    drugs?
    DÁVILA-REYES:   Grab it and run off with it, and try
    to see -- keep myself from being
    hurt, or defend myself, if it came to
    that.
    THE COURT:      If the one that had the drug didn't
    want to give it to you, what would
    you do? If somebody came to take the
    drug away from him, what would you do
    as an enforcer?
    DÁVILA-REYES:   Well, in order to hold up the person
    who has the drugs, they would have to
    hold me up as well because I am the
    one there protecting the drugs.
    THE COURT:      And what would   you     do   to   defend
    yourself?
    DÁVILA-REYES:   Well, at that point it would be to
    defend my life because that person is
    coming to hurt me.
    -42-
    THE COURT:      What would you do -- what would you
    use to defend your life?
    DÁVILA-REYES:   To run, to try to fight -- maybe
    fight the person as a very last, last
    recourse, maybe, if the person was
    armed, but I don't know. I never had
    that experience, Your Honor.
    THE COURT:      Why would you need a gun then if you
    would start to run away?
    DÁVILA-REYES:   That’s like -- I don't know. I used
    to say it was like part of the
    uniform.
    The court then turned the witness back over to the government. No
    additional objections were raised at this time.
    After a truncated redirect examination, the district
    court once again took over the questioning, this time in a direct
    critique of the heart of the witness's claim that the government's
    witness had solicited fabricated evidence:
    THE COURT:      [I]f you did not tell [Pérez-Colón]
    anything about anything . . . why
    did you have to make a sworn
    statement?
    DÁVILA-REYES:   . . . I wanted [Torres-Estrada] to
    know that I didn't have any intention
    of hurting him, even though we were
    supposedly enemies . . . .
    THE COURT:      But   since   you   did   not  tell
    [Pérez-Colón] anything about any
    criminal   activity   on   the part
    of . . . Torres-Estrada, then where
    would    [Pérez-Colón]    get   the
    information to fabricate a case
    against   [Torres-Estrada]?    It's
    simple.     If you did not tell
    -43-
    [Pérez-Colón]  anything,    as  you
    mentioned before, of the criminal
    activity of [Torres-Estrada], why
    did you have to tell him to be
    careful?       What    were    they
    fabricating?     What   were   they
    fabricating?
    DÁVILA-REYES:   I don't know.
    THE COURT:      You just mentioned --
    DÁVILA-REYES:   I didn't say he was fabricating.
    THE COURT:      You   just   mentioned   they     were
    fabricating.
    DÁVILA-REYES:   No, I didn't say "fabricating."
    THE COURT:      And your testimony --
    DÁVILA-REYES:   He asked me to tell him so that he
    could pass it on.
    THE COURT:      And your testimony here was that you
    never told [Pérez-Colón] anything
    about [Torres-Estrada].
    DÁVILA-REYES:   No.
    THE COURT:      So how could [Pérez-Colón] tell him
    anything since you did not tell
    [Pérez-Colón] anything about the
    criminal acts of [Torres-Estrada]?
    DÁVILA-REYES:   When he told me that, I as in my cell
    with another --
    THE COURT:      Sir, I don't need an explanation from
    you.    I just want you to tell
    me . . . . What did [Torres-Estrada]
    have to fear from [Pérez-Colón]?
    DÁVILA-REYES:   The same thing he was -- that he
    would hurt him with some other person
    who would be -- could provide
    -44-
    information.       I saw it as an illegal
    act.
    THE COURT:        But since [Pérez-Colón] did not have
    any information from you, then you
    are supposing that somebody else
    could give it.
    DÁVILA-REYES:     I didn't really -- I don't really
    know.   But I simply saw it as an
    illegal movement, and I gave him a
    heads-up.
    THE COURT:        So what you are testifying here then
    is what you perceived or what you
    thought; not really what happened?
    DÁVILA-REYES:     No, it is what happened, because
    those words I used were the words he
    said to me.
    THE COURT:        All right.   But since you did not
    give him any criminal information
    about [Torres-Estrada], then you are
    assuming that somebody else would
    have     given    it     to     harm
    [Torres-Estrada].
    At    this    point,     Varestín     objected     "to   the    Court's   line    of
    questioning" on the grounds that the court was "outdoing the job
    for   the    [g]overnment"       by   improperly    "trying     to   impeach   [the
    defense's] witness."         The district court responded: "I wanted to
    clarify for the jury whether what he is saying is what he really
    saw or did or heard, or something that he is imagining that
    happened."
    Subsequently, Varestín filed a motion for mistrial based
    on    the    trial     judge's    comment   in     front   of    the   jury      that
    -45-
    Dávila-Reyes's "testimony also is not relevant in this case." The
    court denied the motion and explained that defense counsel was
    "the one that raised the issue that his testimony was not relevant
    to this trial, because the [g]overnment was trying to elicit
    information through his testimony that was not relevant to the
    trial, and I just said, yes, his testimony is not relevant in this
    case . . . ."
    Following the court's decision, the other defendants
    sought to join in Varestín's motion.      Raymundí also requested a
    jury instruction to disregard the court's comment. However, since
    Dávila-Reyes was Varestín's witness, and Varestín expressed his
    preference to withhold a specific instruction on the relevancy
    comment until the jury instructions at the end of trial to avoid
    bringing more attention to the matter than necessary, the court
    stated that it would defer to Varestín's preference. Nevertheless,
    later that day the court told the jury:
    I just want to remind you that as I told you at the
    beginning of the case, you as jurors are the sole
    judges of the facts and the credibility of the
    witnesses.    Comments that I may have made and
    comments by the Court or the attorneys are not
    considered as evidence, nor [should] my comments or
    my questions . . . be an indication to you how to
    view that evidence nor how -- what I think about the
    evidence.
    As promised, the court also addressed the matter in its final
    instructions to the jury before they began deliberation:
    -46-
    During the course of the trial, I occasionally have
    asked questions of a witness. Do not assume that I
    hold any opinion on the matters to which my questions
    may relate. The Court may ask questions simply to
    clarify a matter not to help one side of the case or
    hurt the other. Remember at all times that you as
    jurors are at liberty to disregard all comments of
    the Court in arriving at your own findings as to the
    facts. So anything I may have said during the course
    of the trial is not evidence also.
    At this juncture, the court also instructed the jury on
    weighing the credibility of cooperating witnesses:
    [Marrero-Martell, Pérez-Colón, and Figueroa-Agosto]
    have provided evidence on their agreements with the
    government, participated in the crime charged
    against the defendants, and expect to receive the
    benefit of a recommendation from the government to
    receive a lower sentence in exchange for providing
    information.    Some people in this position are
    entirely truthful when testifying. Still, you should
    consider the testimony of these individuals with
    particular caution. They may have had reason to make
    up the stories or exaggerate what others did because
    they want to help themselves.6
    6   The court additionally instructed:
    You should also ask yourselves whether there was
    evidence that a witness testified falsely about an
    important fact, and ask whether there was evidence
    that at some other time, a witness said or did
    something or didn't say or do something that was
    different from the testimony the witness gave during
    trial.   But keep in mind that a simple mistake
    doesn't mean that a witness wasn't telling the truth
    as he or she remembers it. People naturally tend to
    forget some things or remember them inaccurately. So
    if a witness misstated something, you must decide
    whether it was because of an innocent lapse in memory
    or an intentional deception.     The significance of
    your decision may depend on whether the misstatement
    is about an important fact or about an unimportant
    detail.
    -47-
    The defendants renewed their challenges to the court's
    comments about the relevance of Dávila-Reyes's testimony in their
    post-verdict Rule 33 motions. The district court declined to find
    that its comments warranted a new trial.             Rather, the court,
    assuming arguendo that the comments were prejudicial given the
    centrality of Dávila-Reyes's testimony to the defense's trial
    strategy     of   impeaching   the    credibility   of   the     cooperating
    witnesses,    determined that its curative instructions "dispelled"
    any prejudice.       Moreover, the court noted that any error was
    harmless because "neither D[á]vila[-Reyes'] testimony nor any
    comment by the court would be enough to overcome the overwhelming
    evidence of guilt presented against the defendants at trial." That
    "overwhelming evidence" was the testimony of the government's
    cooperators, i.e., the testimony that Dávila-Reyes's testimony was
    aimed at discrediting.
    2. Testimony of David Rivera-Rivera
    Varestín also called his coworker Rivera-Rivera, who
    works as a refrigeration technician, to testify.               Rivera-Rivera
    was on the December 2009 trip to the Dominican Republic and he
    testified that, contrary to what Marrero-Martell and Pérez-Colón
    had stated, the purpose of the trip was to "enjoy [them]selves and
    get to know Santo Domingo," and generally to "have fun."            He also
    stated that "nothing happened" during the boat trip aside from
    -48-
    "drinking on the way."      Rivera-Rivera said that he did not see
    anyone with guns or drugs during the trip or hear anyone talking
    about illegal acts such as murder.
    On   redirect    examination,   Varestín's   counsel    asked
    Rivera-Rivera how many beers he drank on the boat trip.            The
    government objected as beyond the scope, which the court overruled.
    Rivera-Rivera then answered, "several beers," which prompted the
    following exchange:
    THE COURT:         Several is what number?
    VARESTÍN:          Can you be more specific?
    RIVERA-RIVERA: Around seven or eight beers.
    THE COURT:         During the trip?
    RIVERA-RIVERA: During the trip.
    THE COURT:         15 hours?
    RIVERA-RIVERA: Well, exactly -- I don't recall the
    exact time it took for the trip, but
    it was during the -- it was during
    the trip.
    THE COURT:         You left at 7:00 p.m., Puerto Rico.
    RIVERA-RIVERA: Uh-huh.
    THE COURT:         And you got to the Dominican Republic
    around 1:00 or 2:00 in the afternoon
    the next day?
    RIVERA-RIVERA: Yes.
    THE COURT:         How many hours is that? You do the
    arithmetic and tell me.
    -49-
    RIVERA-RIVERA: I can't tell you exactly. I don't
    recall.
    THE COURT:     Okay. Let's start at 7:00 p.m. until
    midnight. How many hours?
    RIVERA-RIVERA: From 7:00 to 10:00?
    THE COURT:     You know I didn't say 10:00.     You
    knew I said midnight. How many hours
    are there?
    RIVERA-RIVERA: Five hours.
    THE COURT:     And from midnight to 7:00 a.m., how
    many hours are there?
    RIVERA-RIVERA: Seven hours.
    THE COURT:     Plus five the night before are how
    many?
    RIVERA-RIVERA: Plus five of the previous night -- I
    am lost again.
    THE COURT:     Well, find yourself. Five the night
    before. From 7:00 p.m. to midnight,
    that's five.   And from midnight to
    7:00 in the morning, how many hours?
    RIVERA-RIVERA: Seven.
    THE COURT:     Plus the five the night before, how
    many is that?
    RIVERA-RIVERA: 12.
    THE COURT:     And from 7:00 a.m. until noon, how
    many are there?
    RIVERA-RIVERA: Five.
    THE COURT:     Plus 12 already, how many is that?
    RIVERA-RIVERA: 17.
    -50-
    THE COURT:      And one more, from noon to 1:00
    o'clock or 2:00 o'clock, how many
    more?
    RIVERA-RIVERA: About 18 hours.
    THE COURT:      And that's how long the trip took?
    RIVERA-RIVERA: Approximately.       I   don't   recall
    exactly.
    THE COURT:      But approximately 17 hours?
    RIVERA-RIVERA: More or less.
    THE COURT:      And you had only seven beers during
    those 17 hours?
    RIVERA-RIVERA: Around, more or less.    Perhaps one or
    two more.
    There were no objections to this inquiry, nor did any of the
    defendants raise the issue in their post-verdict Rule 33 motions.
    C.   Analysis
    Where the Government builds its case against criminal
    defendants predominantly on cooperating witness testimony, which
    the jury must weigh against the testimony of key defense witnesses,
    "the [district] court must take particular care to avoid any
    appearance that it favors the government's view of the case."
    Rivera-Rodríguez, 761 F.3d at 120 (citation omitted); see also
    United States v. Barnhart, 
    599 F.3d 737
    , 745 (7th Cir. 2010);
    United States v. Tilghman, 
    134 F.3d 414
    , 416 (D.C. Cir. 1998)
    ("Because juries, not judges, decide whether witnesses are telling
    the truth, and because judges wield enormous influence over juries,
    -51-
    judges may not ask questions that signal their belief or disbelief
    of witnesses." (citing United States v. Wyatt, 
    442 F.2d 858
    , 859-
    61 (D.C. Cir. 1971)). Here, the government's proof relied heavily
    -- and in many respects crucially -- upon the testimony of three
    cooperating    witnesses:        Marrero-Martell,      Pérez-Colón,     and
    Figueroa-Agosto. If the jury did not believe testimony from those
    cooperating witnesses, the government's case largely fell apart as
    to the specific crimes charged.
    We   turn   first    to   the    trial   judge's   comment   that
    Dávila-Reyes's testimony was flat-out "not relevant in this case."
    To the contrary, Dávila-Reyes's testimony was highly relevant and
    central to the defense.       He directly attacked the credibility of
    Pérez-Colón by stating that Pérez-Colón was offering money for
    information that could be "bulk[ed] . . . up" to incriminate the
    defendants.    Earlier testimony had revealed that Pérez-Colón was
    in touch with the other cooperating witnesses and Junior Cápsula
    on the subject of cooperating with the government.             So Dávila-
    Reyes's testimony about Pérez-Colón, if believed, undercut more or
    less the entire prosecution case by suggesting that the cooperators
    were fabricating testimony to take down a rival faction.
    We have previously noted that adding to the evidence by
    weighing in on witness credibility amounts to "per se misconduct"
    (i.e., per se appearance of bias), Márquez-Pérez, 835 F.3d at 158;
    -52-
    see also Ayala-Vázquez, 751 F.3d at 27-28, based on the Supreme
    Court's decision to reverse in Quercia, where the trial judge added
    to the evidence by expressing his opinion to the jury that the
    defendant's body language while on the witness stand indicated
    that he was lying, see 
    289 U.S. at 471-72
    . Distorting the evidence
    is similarly problematic from the standpoint of signaling bias,
    see Márquez-Pérez, 835 F.3d at 158, especially when the distortion
    impacts a critical issue such as the reliability of the testimony
    offered by three cooperating witnesses, which in this case was
    instrumental to the government's case against the defendants.            The
    trial judge's relevance comment did just that, "put[ting] his own
    experience, with all the weight that could be attached to it, in
    the scale against the accused."          Quercia, 
    289 U.S. at 471
    .      The
    off-hand comment, which did not serve "to assist the jury in
    reaching the truth," 
    id. at 472
    , signaled to the jury that they
    should disregard Dávila-Reyes's crucial and quite relevant defense
    evidence as not relevant. By undermining Dávila-Reyes's testimony
    in this manner, the judge's comment also undermined the defense
    theory that the cooperating witnesses each had a motive to lie.
    We could hardly say then that dismissing Dávila-Reyes's
    testimony   as   irrelevant   to   the    case   did   not   cause   serious
    prejudice, for there is a "reasonable probability" that the jury
    would have weighed the evidence differently (and thus reached a
    -53-
    different outcome) had the trial judge not tipped the scales
    against Dávila-Reyes's testimony. Márquez-Pérez, 835 F.3d at 161.
    In other words, if the judge had not intervened, the jury may have
    credited Dávila-Reyes and disbelieved the cooperators.
    To be sure, the government did put other witnesses on
    the stand. Agent González implicated Martínez by naming him as an
    employee of the known drug distributor, Luna-Archeval.                          Agent
    Mayoral testified that he stopped Collazo's boat for a border
    search on its way back from the Dominican Republic, but there were
    neither drugs nor money on the boat.                     The car dealership and
    insurance company witnesses implicated Collazo in a potential
    money-laundering scheme through their testimony about his purchase
    of   a   Porsche     GT2    and     an   insurance       policy    for   that      car.
    Additionally, multiple federal law enforcement agents testified
    about interviews they conducted with Pérez-Colón, Marrero-Martell,
    Varestín,    and   Rivera-Rivera         in   the   Dominican     Republic,     which
    occurred    during    the    trip    described      in    the   testimony     of   the
    cooperating    witnesses      as    a    thwarted    attempt      to   kill   Colonel
    González.     During those interviews, the men told law enforcement
    that the purpose of the trip was pleasure.                        Thus, the trial
    narratives    of   the     cooperating        witnesses   are     what   effectively
    connected the dots and filled in the blanks as to the defendants'
    alleged participation in the drug trafficking conspiracy.                          For
    -54-
    instance, Agent González's testimony that Martínez worked for
    Luna-Archeval packs much less of a punch without Pérez-Colón's and
    Figueroa-Agosto's detailed explanations of how Martínez accepted
    delivery    of    and   stored    the      drug     inventory.           Although      the
    independent      evidence    about    Collazo's      sketchy         purchase    of    the
    Porsche GT2       and    insurance         policy         is     certainly        enough
    circumstantial       evidence        to     raise     a        red     flag,     it        is
    Marrero-Martell's explanation of the money-laundering scheme and
    the practice of paying with checks from Electroamerica that truly
    completes the picture.           While law enforcement testimony places
    Varestín in the Dominican Republic in December 2009 with members
    of the drug trafficking organization, only the testimony of the
    cooperating      witnesses    specifically          connects         Varestín    to    the
    organization's operations. Thus, on balance, the testimony of the
    cooperating witnesses was the crux of the government's case against
    the defendants, and for Varestín and Raymundí, provided the lion's
    share of the potentially incriminating evidence against them.
    The trial judge attempted to explain away his relevance
    comment    as    actually    supporting      the    defense's         objection       to   a
    government question regarding where Dávila-Reyes sourced his drugs
    when he was involved in drug trafficking activities. However, the
    record paints a different picture. The district court denied both
    of Raymundí's objections to this line of questioning.                           Varestín
    -55-
    then lodged a third objection, reiterating the view that the
    specific information the government was attempting to elicit was
    not   relevant   to   the   trial.    Instead   of   expressly   ruling    on
    Varestín's relevancy objection, the trial judge responded that
    "[Dávila-Reyes's] testimony also is not relevant in this case."
    In context, the comment reads more like an off-the-cuff opinion
    about the weight the judge gave to the testimony that Dávila-Reyes
    had offered rather than a specific evidentiary ruling (the latter
    being well within the province of the trial judge).          Seen in this
    light, the comment actualized the risk that the jury, which is
    susceptible to being influenced by the judge's "lightest word or
    intimation," Starr, 
    153 U.S. at 626
    , would be swayed by the judge's
    view in its determination of whether and to what extent to both
    weigh and credit Dávila-Reyes's testimony.
    Moreover, the trial judge's curative instructions here
    were "too little too late" because, where the reliability of
    witness testimony is so strongly implicated (here, that of the
    cooperating witnesses against that of the defense witnesses),
    "such interference with jury fact-finding cannot be cured by
    standard jury instructions."         Tilghman, 
    134 F.3d at
    421 (citing
    United States v. Filani, 
    74 F.3d 378
    , 386 (2d Cir. 1996)).                The
    analysis might be different had the judge specifically withdrawn
    the comment by explaining that he was by no means suggesting that
    -56-
    the witness's testimony on direct was not relevant to the case,
    but that is not what transpired here.7
    All that being said, we need not and do not rest our
    holding on the single comment about the relevance of Dávila-Reyes's
    testimony.    As we have detailed above, the trial judge's further
    intercessions consistently reinforced the pro-government message
    conveyed by the relevant comment.         The trial judge "took over the
    prosecutor's role" with his questioning of Dávila-Reyes after
    redirect examination.      Rivera-Rodríguez, 761 F.3d at 120.          The
    court began with an innocuous question, asking Dávila-Reyes to
    explain why he needed to make a sworn statement about Pérez-Colón's
    attempt to recruit him in prison if indeed he did not provide any
    information that could be leveraged against Torres-Estrada's crew.
    Dávila-Reyes explained that he did it to protect himself so
    Torres-Estrada    would   not   think   Dávila-Reyes   had   crossed   him.
    Seeking this type of clarification about the witness's testimony
    surely falls on the permissible side of the line in terms of
    assisting the jury, especially because it appears that the defense
    7 One might expect the defendants to have requested a better
    curative instruction recanting the relevancy comment given its
    prejudicial potential, but the defendants had different ideas
    about how best to handle the judge's comment. Raymundí sought a
    specific instruction that the jury disregard the relevance
    comment. On the other hand, Varestín (who called the witness) did
    not want to call more attention to the matter and thus preferred
    to withhold a specific instruction until the end of trial.
    -57-
    caused   some   initial   confusion       by   mistakenly   suggesting    that
    Dávila-Reyes had made a sworn statement in this case, when in fact,
    the sworn statement pertained to a different case. What followed,
    however, shows the trial judge crossing a line to impermissibly
    argue the prosecution's case.
    As if cross-examining Dávila-Reyes, the trial judge
    asked how, if Dávila-Reyes did not provide any information to
    Pérez-Colón, Pérez-Colón would be able to fabricate a case against
    Torres-Estrada    and   his   crew.       This   appears    to   have   been    a
    rhetorical question because the judge commented, "[i]t's simple,"
    before pressing Dávila-Reyes again on why he wanted to give
    Torres-Estrada a heads-up and nearly demanding that he answer,
    "What were they fabricating?          What were they fabricating?"           The
    court continued this line of questioning for another page of
    transcript, trying to get Dávila-Reyes to concede that he had no
    first-hand knowledge of whether or not someone else might have
    given information to Pérez-Colón.            The exchange culminated with a
    leading question that likely further discredited Dávila-Reyes's
    testimony in the eyes of the jury:             "So what you are testifying
    here then is what you perceived or what you thought; not what
    really happened?"       Cf. Rivera-Rodríguez, 761 F.3d at 123 ("The
    court's assumption of the prosecutor's role in questioning the
    cooperating     witnesses,    and   its    use   of   leading    questions     to
    -58-
    facilitate the inquiry, undoubtedly made the trial more efficient,
    but they also created the impression that the court favored the
    government's version of events."). One might expect the government
    to impeach a hostile witness this way on cross-examination, but
    coming from the judge, it "suggest[ed] to the jury that the court
    itself ha[d] a stake in the jurors' understanding" the witness's
    testimony a certain way.         Rivera-Rodríguez, 761 F.3d at 121; see
    also id. at 121-22 ("In short, the court's [line of questioning]
    was a much more effective way to accomplish what the prosecutor
    was trying to accomplish, and it added to the overall sense that
    the judge was helping the government make its case."); United
    States v. Hickman, 
    592 F.2d 931
    , 935 (6th Cir. 1979) ("The district
    judge's brilliant redirect examination would have been entirely
    proper had it been done by the prosecutor.").            In sum, given the
    centrality of Dávila-Reyes's testimony to the defense's case, the
    court's      intervention   compounded      the   appearance   of   bias   and
    resulting prejudicial effect created by the earlier comment on the
    relevance of Dávila-Reyes' testimony and thus similarly could not
    be   cured    by   boilerplate   jury   instructions.      Compare   Rivera-
    Rodríguez, 761 F.3d at 123 (finding serious prejudice where the
    judge's interventions in witness testimony "created the impression
    that the court favored the government's version of events"), with
    Ayala-Vázquez, 751 F.3d at 24 (finding no prejudice where the
    -59-
    court's comments bore on eliciting relevant, topical information),
    and Márquez-Pérez, 835 F.3d at 161–62 (finding no prejudice where
    the court's conduct related to counsel's courtroom behavior and
    not the merits of the case). The impact is especially severe here
    because   the   judge's   intervention   took   place    during   the
    presentation of important testimonial evidence in the defense case
    regarding the credibility of the cooperating witnesses and their
    potential motivations to lie.   See Márquez-Pérez, 835 F.3d at 161
    ("[M]isconduct during the presentation of critical evidence is
    more likely to prejudice than that during testimony irrelevant to
    the defendant." (citations omitted)).
    In terms of its cumulative effect, the trial judge's
    "enforcer" questioning during the government's cross-examination
    of Dávila-Reyes weighs in favor of the trial judge showing an anti-
    defense witness (or pro-cooperating witness) bias.      The same goes
    for the trial judge's subsequent questioning of Rivera-Rivera,
    which is concerning because it shows that the judge continued
    playing prosecutor even after the defense specifically objected
    that the court was "outdoing the job for the Government" with its
    questioning of Dávila-Reyes.    In any event, because no defense
    counsel objected contemporaneously, our review is for plain error
    (although as we have noted, this does not make much of a difference
    as far as the third and fourth prongs of the test are concerned).
    -60-
    Nevertheless, evaluated for their cumulative effect established by
    the aforementioned interventions into Dávila-Reyes's testimony,
    the error is both clear and obvious.         See Rivera-Rodríguez, 761
    F.3d at 112; cf. Filani, 
    74 F.3d at 387
     ("It is 'clear error for
    a trial judge to ask questions bearing on the credibility of a
    defendant-witness prior to the completion of direct examination,'"
    as well as "[w]hen a judge joins in cross-examination," because it
    creates a "'tag team' situation," which gives the jury "a powerful
    [and impermissible] impression that the district court agreed with
    the government that the defendant was guilty[.]" (quoting United
    States v. Victoria, 
    837 F.2d 50
    , 55 (2d Cir. 1988))).
    The "enforcer" questioning leaves a particularly bad
    taste because after overruling the defense's objection to the
    government's questions on that subject, the trial judge took over
    the cross-examination of Dávila-Reyes and asked leading questions
    about his past willingness to use force to protect his life and
    his drugs when he worked as an enforcer. Viewed in isolation, the
    exchange   would   likely   be   a   permissible   effort   to   "clear   up
    inadvertent witness confusion" about what the role of an enforcer
    is in a drug operation.      Hickman, 
    592 F.2d at 933
    .           But in the
    context of the judge's other interactions with Dávila-Reyes, and
    especially given the length of the exchange, the judge's comments
    amounted to cross-examination aimed at developing reasons not to
    -61-
    believe the witness.
    Relatedly, the government contends that the fact that
    the jury acquitted Varestín, Martínez, and Collazo on Count 1 (the
    drug importation conspiracy charge) "shows that the jurors were
    able to consider the evidence free from any bias that the court's
    comments may have betrayed."     This logic fails to persuade us.
    Without overly psychoanalyzing the jury, the acquittals on Count 1
    merely signify that there was only enough evidence to sustain a
    conviction on that count for one of the four defendants.
    The optics deteriorate further when we factor in the
    court's badgering of Rivera-Rivera to come up with an exact number
    of beers he drank on a boat trip he took seven years earlier and
    to calculate the exact duration of that boat trip while on the
    stand. Rivera-Rivera's credibility was crucial to the defendants.
    He was the only one on the boat trip to the Dominican Republic in
    December 2009 without ties to the drug trafficking organization.
    His testimony that the trip was a vacation and that he did not see
    or hear any criminal activity on the boat called into question the
    cooperators' testimony that the purpose of the trip was to kill
    Colonel González.   The judge's extended toying with Rivera-Rivera
    over how long the trip lasted and how many beers he drank was
    classic   cross-examination   aimed   at   discrediting   the   witness,
    making "the jury more inclined to believe the government's version
    -62-
    of events." Rivera-Rodríguez, 761 F.3d at 123. Each of these two
    interventions may not have crossed the line alone, see, e.g.,
    Márquez-Pérez, 835 F.3d at 158 (noting that a trial judge's
    impatience,       annoyance    or     short     temper     are     not     sufficient
    conditions    for    a    reversal    on    misconduct),     but    together    they
    reinforce our perception that the judge's comments created the
    appearance of bias because they show a pattern of different
    treatment    of    the    defense    witnesses      than   of    the     cooperating
    witnesses. See Tilghman, 
    134 F.3d at 421
    .
    Importantly,      the     judge's       inquiries      were      visibly
    "one-sided."      Rivera-Rodríguez, 761 F.3d at 121.               In other words,
    this was not a case in which the district court was even-handed in
    its aggressive questioning of witnesses both for the defense and
    the prosecution.
    These       two   additional          instances       of      "intrusive
    questioning," Filani, 
    74 F.3d at 387
    , compounded the prejudice to
    defendants that we have identified with respect to the judge's
    relevance comment and his questioning of Dávila-Reyes after the
    defense's redirect examination.               Varestín and Raymundí feel the
    cumulative effect rather acutely because Rivera-Rivera's testimony
    created a material discrepancy as to the cooperating witnesses'
    testimony about the purpose of the December 2009 trip to the
    Dominican    Republic.         We    thus   find    that   these        interventions
    -63-
    (although not contemporaneously objected to at trial) amount to
    plain error when considered in the aggregate.             The trial judge's
    perceptible partiality impaired the integrity and fairness of the
    trial.    Given the severity of the prejudice to the defendants
    vis-à-vis the tipping of the scales in favor of the credibility of
    the cooperating witnesses, these interventions could not be cured
    by the standard instructions offered by the trial judge.
    To facilitate courtroom administration, we generally
    afford trial judges "wide discretion to interject questions in
    order to throw light upon testimony or expedite the pace of a
    trial."   Logue, 
    103 F.3d at 1045
    .          To that end, because reading
    signs of bias from the paper record without first-hand knowledge
    of the atmosphere and tone in the courtroom is a delicate task,
    the standard of review we deploy for claims of judicial misconduct
    is a deferential one (and reasonably so).                 Cognizant of the
    challenges of managing a complex eleven-day trial, we nevertheless
    find that, the cumulative effect of the trial judge's comment that
    Dávila-Reyes's testimony was irrelevant to the case plus the
    judge's "continued one-sided interventions" (even after objection
    from   defense   counsel)   created    an    appearance    of   anti-defense
    witness    bias.       Without       the    trial    judge's      prejudicial
    interventions,     "there   is   a   reasonable     probability    that   [the
    defendants] would not have been convicted." Rivera-Rodríguez, 761
    -64-
    F.3d at 123. Once the judge signaled to the jury his disbelief of
    (or his indication to disregard the testimony of) the defense
    witnesses and, by extension, the defense theory, his comments
    bolstered    the   government's   case    and   seriously   prejudiced    the
    defendants. In doing so, the judge improperly altered the jurors'
    ability to evaluate competing testimony on their own.              See United
    States v. Meléndez-Rivas, 
    566 F.3d 41
    , 50 (1st Cir. 2009). Because
    this judicial misconduct infringed upon all four defendants' right
    to a fair trial, we vacate their convictions and remand for a new
    trial.
    III.   Brady Issues
    The    defendants   collectively    raise   a   host    of   other
    issues.8    Because the relief we order due to the trial court's one-
    8 Among the various issues raised, Varestín alleges that the
    jury selection process was inadequate because the district court
    prevented the defense from exercising challenges for cause, which
    he claims amounts to a structural error requiring a new trial.
    Collazo echoes this argument and adds that it was an abuse of
    discretion specifically not to excuse a particular juror for cause.
    Additionally, Varestín and Raymundí -- joined by both Martínez and
    Collazo -- claim that the Government's elicitation of testimony
    from its cooperating witnesses about the planned murder of Colonel
    González and the killing of Marrero-Martell's nephew, Menor,
    violated the district court's pre-trial ruling (reiterated at
    sidebar)   and   thus  amounted    to   prejudicial   prosecutorial
    misconduct. Relatedly, Varestín asserts that the court's failure
    to translate Pérez-Colón's testimony about the death of Menor into
    English constitutes a reversible violation of the Jones Act, 
    48 U.S.C. § 864
    .     Martínez adds his own take on prosecutorial
    misconduct, which is that the Government both engaged in improper
    questioning of defense witness Esmira Negrón-Irlanda (Martínez's
    -65-
    sided intercessions equals or exceeds the potential relief that
    could result from our disposition of those other issues, and
    because the other issues are unlikely to arise again in the same
    way, we need neither reject nor accept any party's arguments
    concerning any of these issues.   There is one exception:   to make
    clear that a long-running Brady dispute in this case has been put
    to bed, we consider and reject defendants' appeal as far as it
    concerns that issue. Our reasoning follows.
    A.   Background
    Following trial but prior to sentencing, Varestín's
    counsel (an Assistant Federal Public Defender) was appointed to
    represent Carlos Ochoa-Rocafort ("Ochoa"), a former prison guard
    facing an indictment on corruption charges in an entirely separate
    criminal case.   See United States v. Ochoa, No. 17-cr-00065–JAG
    mother)   on   cross-examination   and   improperly   vouched   for
    cooperating   witness   Pérez-Colón   during   closing   arguments.
    Raymundí, Martínez, and Collazo also add a challenge based on the
    cumulative effect of the various trial errors. To his personal
    list of trial grievances, Collazo adds contentions that the
    district court wrongly made public the defense's sealed ex parte
    motion for records of a boat parked in a lot outside Collazo's
    place of business and that the Government improperly coached a
    witness. Martínez, for his part, adds that the delayed sentencing
    of Figueroa-Agosto and Pérez-Colón, as well as a denial of access
    to daily transcripts, deprived him of a fair trial. Raymundí and
    Collazo also challenge the quashing of a witness subpoena aimed at
    showing that an important government witness testified to facts
    that he had not previously included when interviewed by law
    enforcement.     Finally, Varestín submits that his 235-month
    sentence was procedurally unreasonable because it was based on a
    clearly erroneous drug quantity finding.
    -66-
    (D.P.R. Feb. 9, 2017).          Ochoa informed Varestín's counsel that
    Marrero-Martell, Pérez-Colón, and Junior Cápsula may have assisted
    the government in its investigation of Ochoa's case.                 Prior to
    sentencing, Varestín requested that the government verify whether
    Marrero-Martell, Pérez-Colón, or Figueroa-Agosto were working as
    confidential informants at the time of the defendants' trial and,
    if they were, whether any such relevant information fell within
    the government's disclosure obligations.
    At Varestín's sentencing hearing on March 14, 2017, his
    attorney     indicated   that   the   government   had   responded    to   the
    attorney's emails about the confidential informant issue but had
    not meaningfully addressed the request because it was allegedly
    unable to get an update from the prosecutor who tried the case
    (who   was    no   longer   a   full-time    employee    in   the    office).
    Consequently, Varestín asked the district court to order the
    government to disclose whether Marrero-Martell and Pérez-Colón
    were indeed confidential informants during Varestín's trial and,
    if so, to disclose the nature of any agreements in existence.              In
    response, the government stated that it had still not been able to
    get in touch with the trial prosecutor but that it believed it had
    complied with all of its discovery obligations "up until [the]
    trial date."
    On September 14, 2017, Varestín filed a written motion
    -67-
    reiterating the request made at sentencing, which the other three
    defendants moved to join.           In response, on October 12, 2017, the
    government     asserted      that     the     defendants'    "'discovery-like'
    request" lacked "a prima facie showing of relevance, particularly,
    at this juncture of the criminal matter," and that the defendants'
    filing of notices of appeal had nevertheless divested the district
    court of jurisdiction over the matter.                Citing to various cases,
    including Brady v. Maryland, 
    373 U.S. 83
     (1963) and Giglio v.
    United States, 
    405 U.S. 150
     (1972), Varestín objected to the
    government's response by pointing out that its disclosure duty was
    ongoing and that the defense had established its burden of proof
    that   the   government      had    violated    its   obligation    to   disclose
    specified exculpatory and impeachment material.                    In Varestín's
    eyes, the government had failed to disclose potential impeachment
    evidence     despite   the    defense's     persistent    requests,      and   this
    continuing non-disclosure was prejudicial because it hampered the
    defense's ability to adequately cross-examine the cooperating
    witnesses about whether they were also confidential informants in
    another unrelated case, teeing up what we have described as a
    classic credibility contest.
    The   district    court    denied    Varestín's    Brady     motion,
    rendering moot the co-defendants' motions to join.                 Varestín then
    filed an ex parte motion for reconsideration, as well as a motion
    -68-
    to compel an array of Brady and Giglio materials pertaining to the
    cooperating witnesses.   Martínez moved to join the latter motion.
    Without   explanation,   hearing,   or   in   camera    review   of   the
    undisclosed material, the district court denied the first motion,
    rendering the second motion moot.
    On appeal, Varestín and Collazo (joined by Martínez and
    Raymundí) argued that the district court abused its discretion in
    denying    their     "post-conviction    motions       concerning     the
    [g]overnment's failure to comply with its affirmative, ongoing
    duty to disclose exculpatory and impeachment evidence" under Brady
    and Giglio to such an extent that a new trial was warranted.
    Citing United States v. Rosario-Peralta, 
    175 F.3d 48
    , 55-57 (1st
    Cir. 1999), the government responded that we should remand the
    case to the district court (while retaining jurisdiction) to more
    fully develop the record in the interest of facilitating our
    review.   In light of the parties' briefing on this issue, we
    ordered a limited remand to a different district court judge to
    supplement the record on the question of "whether the government
    violated its disclosure obligations" under Brady or Giglio.
    On remand, Varestín (joined by all of his co-defendants)
    filed a motion that effectively sought three forms of relief.
    First, the defense requested an evidentiary hearing on their Brady
    and Giglio claims.     Second, the defense asked the court for an
    -69-
    order compelling the government to confirm whether Marrero-Martell
    and Pérez-Colón were confidential informants before, during, or
    after the trial and, if they were, to produce their unredacted
    confidential informant file detailing any undisclosed benefit or
    agreement.    Third, they asked the court to compel the production
    of a six-page document containing a list of people against whom
    Junior Cápsula planned to testify (although he never did testify
    in this case), which the government presented to the trial judge
    during an ex parte sidebar but which was never turned over to the
    defense.
    On   March 25,   2020,   after   reviewing   the    parties'
    submissions,      the   district   court   denied   Varestín's   motion,
    rendering moot those of his co-defendants. By the district court's
    assessment, the defendants simply had not made a sufficient showing
    on remand to merit a hearing as to whether the government had
    violated its disclosure obligations.          Because "[t]he threshold
    showing for securing an evidentiary hearing on a Brady claim is
    lower than the necessary showing for establishing a Brady claim,"
    the court reasoned that the defendants had therefore "also failed
    to show entitlement to a Brady or Giglio order on the merits."
    The defendants' timely appeals of the district court's ruling are
    presently before us through their consolidation with the original
    appeals.
    -70-
    B.    Analysis
    We review the district court's Brady and Giglio rulings
    for abuse of discretion.        United States v. Caro-Muñiz, 
    406 F.3d 22
    , 29 (1st Cir. 2005).         Likewise, our review of the district
    court's denial of an evidentiary hearing in the Brady context is
    for abuse of discretion.      See United States v. Connolly, 
    504 F.3d 206
    , 220 (1st Cir. 2007).
    "A defendant's right to due process is violated when the
    prosecution suppresses evidence that is both favorable to the
    accused and material either to guilt or innocence." Moreno-Morales
    v. United States, 
    334 F.3d 140
    , 145 (1st Cir. 2003) (citing Brady,
    
    373 U.S. at 87
    ).        The government's disclosure obligations under
    Brady also extend to evidence that the defense could have used to
    impeach the prosecution's key witnesses.          See 
    id.
     (citing Giglio,
    
    405 U.S. at 154
    ).       This is an independent duty of the prosecution
    that exists regardless of whether the defendant requests favorable
    evidence from the government. See Kyles v. Whitley, 
    514 U.S. 419
    ,
    433-34 (1995).
    The defendant's burden is to show that the allegedly
    suppressed evidence is "material," meaning that "its suppression
    undermines confidence in the outcome of the trial." United States
    v. Bagley, 
    473 U.S. 667
    , 678 (1985).            To prevail on a Brady or
    Giglio   claim,   the    defendant   must   establish   three   conditions:
    -71-
    "[t]he evidence at issue must be favorable to the accused, either
    because it is exculpatory[] or because it is impeaching; that
    evidence must have been suppressed by the State, either willfully
    or inadvertently; and prejudice must have ensued."    Strickler v.
    Greene, 
    527 U.S. 263
    , 281-82 (1999); accord United States v. Peake,
    
    874 F.3d 65
    , 69 (1st Cir. 2017). Unlike in the sufficiency of the
    evidence test, the prejudice element in this test considers whether
    in the absence of the suppressed evidence, the defendant "received
    a fair trial, understood as a trial resulting in a verdict worthy
    of confidence."   Kyles, 
    514 U.S. at 434
    ; see also Peake, 874 F.3d
    at 69 (defining a defendant's chances of success in terms of
    whether there is "'a reasonable probability that, had the evidence
    been disclosed to the defense' in a timely manner, 'the result of
    the proceeding would have been different.'" (quoting Connolly, 
    504 F.3d at 213
    )).    On balance, we assess materiality "collectively,
    not item by item." Moreno-Morales, 
    334 F.3d at
    146 (citing Kyles,
    
    514 U.S. at 436
    ).   When a defendant's challenge is based on newly
    discovered Brady or Giglio material, he must also establish that
    it "was unknown or unavailable to him at the time of trial," and
    that his inability to discover the evidence was not the product of
    his own "lack of diligence." Peake, 874 F.3d at 69 (quoting United
    States v. Maldonado-Rivera, 
    489 F.3d 60
    , 66 (1st Cir. 2007)).
    -72-
    In the Brady context, evidentiary hearings "are the
    exception rather than the rule."           Connolly, 
    504 F.3d at 220
    .        To
    obtain a hearing, "the defendant must make a sufficient threshold
    showing that material facts were in doubt or dispute."                 United
    States v. Colón-Muñoz, 
    318 F.3d 348
    , 358 (1st Cir. 2003) (citation
    omitted).      "When,     for   example,    the   motion   is   'conclusively
    refuted . . . by the files and records of the case,' an evidentiary
    hearing would be supererogatory."            Connolly, 
    504 F.3d at 219-20
    (alteration in original) (quoting United States v. Carbone, 
    880 F.2d 1500
    , 1502 (1st Cir. 1989)).             It is standard practice to
    resolve motions for evidentiary hearings based on affidavits, even
    where "disputed matters of fact aris[e] from post-trial motions."
    Id. at 220.
    Based   on   the   district     court's    "intricate    web    of
    findings," Peake, 874 F.3d at 72, we see no abuse of discretion in
    its decision that the defendants' claim regarding the suppressed
    material did not merit an evidentiary hearing or an order to compel
    any further production.         Moreover, the information unearthed in
    the supplementary proceeding below conclusively refutes the claim
    that   the   government    improperly      withheld   prejudicial    Brady   or
    Giglio material from the defense.
    On the limited remand, the government finally cleared
    the air about the allegedly withheld Brady and Giglio material.
    -73-
    After reaching out to "all the federal law enforcement agencies
    that had any contact with anyone involved in this case," the
    government represented that the cooperating witnesses were "at no
    time"    confidential       informants.        In   support,    the     government
    submitted an affidavit from the FBI and statements from HSI and
    the Bureau of Alcohol, Tobacco, Firearms and Explosives ("ATF").
    The ATF agent stated that an internal database search revealed
    that none of the cooperating witnesses
    had a signed confidential informant agreement with
    ATF.   One or all of these individuals may have
    provided information to ATF but were ultimately not
    utilized by ATF in a manner that would have required
    them   being   registered    as   ATF   confidential
    informants. ATF policy does not require cooperating
    defendants merely providing information to be
    registered as such.
    The FBI agent's affidavit stated that an internal search revealed
    no record of any of the cooperating witnesses "ever having been
    open as a [confidential informant], or having entered into any
    cooperating agreement directly with the FBI." Nor did any of those
    men   receive     any   "one-time     payments"     or   "any   other   financial
    benefit."        Lastly, an HSI agent stated that the department's
    database of confidential informants did not contain any records of
    the     cooperating       witnesses    "ever     being    documented      as   HSI
    confidential informants."
    In    terms    of   the   relevant      timeline,   the     government
    asserted that the FBI opened its investigation into Ochoa in
    -74-
    August 2016, after the defendants' trial ended.                      It is clear from
    the government's response that Marrero-Martell "never had any
    involvement in the prosecution or investigation of Ochoa."                         Thus,
    the government did not withhold any Brady or Giglio material with
    respect to Marrero-Martell because in addition to not providing
    any    assistance      in    Ochoa's   case,      he    was    not    a     confidential
    informant. Pérez-Colón, on the other hand, did cooperate with the
    FBI in its investigation of Ochoa.                According to the government,
    his involvement dates back to November or December 2016, when Ochoa
    smuggled several illegal cell phones into the federal prison in
    Puerto Rico.        Pérez-Colón allegedly received one of these phones
    from Ochoa and gave it to Junior Cápsula.                        According to the
    government, "[t]he FBI was aware of this" and confiscated the
    phones. Pérez-Colón was released from prison on December 12, 2016.
    Over    a    period    of    time   from   the     day    of    his     release    until
    December 27, 2016, Pérez-Colón "made consensual calls to Ochoa as
    part    of    the     ATF/FBI   investigation          into    Ochoa"       and   allowed
    investigators to download all of the data from these conversations
    from his cellphone.             The government provided the FBI's "302
    Reports" (the FBI's official interview notes) to verify the nature
    of     Pérez-Colón's        assistance.          Nevertheless,        the    government
    maintains that Pérez-Colón "was never paid any money for this from
    any law enforcement agency, was not signed up as a confidential
    -75-
    source,   and    received      no   benefit     for   his   assistance   in   the
    investigation into Ochoa." Instead, it asserts that at this time,
    Pérez-Colón     was   merely    under    "the    same    cooperation   agreement
    entered into evidence at trial in this case."
    As the district court rightly concluded, the defendants'
    attempts to refute the legitimacy of the government's proffer are
    little more than speculative hypotheses.                Chiefly, the defendants
    contend that Pérez-Colón's involvement in the investigation of
    Ochoa must have dated back at least to January 2016, seven months
    prior to the trial.            In support of this theory, they cite a
    302 Report of an interview with an unnamed interviewee dated
    October 28, 2016, in which the writing FBI agent notes that Ochoa
    discussed smuggling contraband into a New York prison with the
    interviewee nine months earlier.9               However, even if Pérez-Colón
    were the unnamed interviewee, all that the report reflects is his
    recollection     of   conversations       with    Ochoa     that   predated   the
    government's investigations.
    9 The defendants also surmise that the investigation of Ochoa
    must have begun prior to August 2016 because Pérez-Colón and Ochoa
    allegedly spoke about the latter's vehicle days before a
    confidential tip prompted a stop and search of Ochoa's vehicle,
    which occurred either in July 2015 or July 2016. As proof, they
    submit an untranslated police report that is erroneously dated
    from both July 2015 and July 2016. However, this inconclusive
    document is off-limits because it is untranslated.             See
    Estades-Negroni v. Assocs. Corp. of N. Am., 
    359 F.3d 1
    , 2 (1st
    Cir. 2004).
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    The defendants suspect that Pérez-Colón must have had a
    "tacit agreement" with law enforcement that predated their July
    2016 trial because otherwise Pérez-Colón would not have assisted
    by making the December 2016 phone calls. They also speculate that
    because Ochoa had been on the government's radar for his corrupt
    conduct since 2012, the government may have "purposefully placed"
    Ochoa in prison with the cooperating witnesses to give them "the
    opportunity to gather information and recruit him."          These bald
    assertions go nowhere.     And despite the defendants' protestations
    in reply that the government should have provided a much more
    bounteous trove of information, the data provided was adequately
    responsive to the defendants' original request as to whether the
    cooperating witnesses had been confidential informants for the
    government before, during, or after trial.
    The bottom line is that Pérez-Colón's cooperation with
    the   FBI   and   ATF's   investigation   into   Ochoa   post-dated   the
    defendants' trial.    See United States v. Jones, 
    399 F.3d 640
    , 647
    (6th Cir. 2005) (noting that, where evidence discovered by a party
    after remand for discovery on the issue of selective prosecution
    "did not exist at the time of trial, it was not Brady material");
    2 Fed. Prac. & Proc. Crim. § 256 (4th ed.) ("[E]xculpatory evidence
    must exist at the time of trial to qualify as Brady material.").
    If Pérez-Colón had not yet assisted with the Ochoa investigation
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    at the time of the defendants' trial, the government could not
    have actually or constructively possessed the details of his
    cooperation, let alone disclosed them to the defense.             See United
    States v. Perdomo, 
    929 F.2d 967
    , 970 (3d Cir. 1991) (stating that
    the prosecution is obligated to produce only evidence that is
    "actually or constructively in its possession or accessible to
    it"); cf. Conley v. United Sates, 
    415 F.3d 183
    , 187 (1st Cir. 2005)
    (finding   a   Brady    violation      where    defendant    "learned     the
    [g]overnment failed to disclose impeachment evidence, including
    [an] FBI memorandum, in its possession prior to trial").
    Even   assuming      that    the     Ochoa-related      materials
    catalogued by the district court on limited remand both fell within
    the scope of the government's disclosure obligations and were
    constructively within its possession, see United States v. Mathur,
    
    624 F.3d 498
    , 504 (1st Cir. 2010) (citing Strickler, 
    527 U.S. at 280-81
    ), their non-disclosure would not have been prejudicial to
    the defendants.   In other words, the newly discovered impeachment
    evidence   relating    to   Pérez-Colón's      involvement   in   the   Ochoa
    investigation would not undermine our confidence in the integrity
    of the verdict.   See Kyles, 
    514 U.S. at 434
    .         At best, the Ochoa-
    related evidence would be cumulative impeachment evidence and thus
    "immaterial under Brady [and Giglio]."           Conley, 415 F.3d at 189;
    see also id. ("Suppressed impeachment evidence, if cumulative of
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    similar impeachment evidence used at trial . . . is superfluous
    and therefore has little, if any, probative value." (emphasis in
    original)).       Pérez-Colón          received      no    additional            benefit   in
    exchange for his assistance apart from that which he derived from
    the very same cooperation agreement pursuant to which he testified
    in    the   defendants'     trial.           All   three    cooperating            witnesses
    testified about the details of their cooperation agreements with
    the    government,       which    for        Pérez-Colón        entailed         scores     of
    interviews with law enforcement as well as taking the stand in
    several      court     proceedings            related      to     drug           trafficking
    prosecutions.        By the terms of his cooperation agreement, which
    includes     a   general     provision          committing        him       to     providing
    information      about     criminal         activity      on     an     ongoing       basis,
    Pérez-Colón's assistance in the Ochoa investigation, without the
    promise     or   receipt    of        any    additional     benefit,         mirrors       the
    impeachment evidence that the defense already put forward through
    its    cross-examination         of    the    witness.          Thus,       even     if    the
    Ochoa-related        materials        did     fall     within         the    government's
    disclosure obligations, the government would not have subverted
    confidence in the jury's verdict by withholding them.
    The six-page document listing the names of the potential
    defendants against whom Junior Cápsula might testify adds nothing
    to the mix in terms of our wholesale assessment of the potential
    -79-
    prejudice caused by the government's suppression of Brady or Giglio
    material.     Even   assuming   for   the   sake   of   argument   that   the
    government improperly withheld the six-page document from the
    defense, the fact remains that Junior Cápsula did not ultimately
    testify in the trial and thus did not need to be impeached.               The
    defendants suggest that the list of people against whom Junior
    Cápsula might testify was material to their case because it
    supported their theory that the cooperating witnesses coordinated
    their testimony out of loyalty to Junior Cápsula (and at the
    expense of Torres-Estrada).       But the defense had already elicited
    testimony about the cooperating witnesses' alleged plan and Junior
    Cápsula's plea and cooperation agreements.               So any testimony
    elicited about the list of people Junior Cápsula might testify
    against would have been cumulative.10
    IV.    Conclusion
    For   the   foregoing     reasons,     we   vacate     all    four
    defendants' convictions and remand for a new trial consistent with
    our resolution of this appeal.
    AFFIRMED IN PART, VACATED, AND REMANDED.
    10Our holding does not prejudge either way whether any of the
    evidence we assume to have been material in Part III of this
    opinion should be admitted at any retrial.
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