Commonwealth v. Barry ( 2019 )


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    SJC-08635
    COMMONWEALTH vs. ANTHONY BARRY
    (and nine companion cases1).
    Middlesex.      October 5, 2018. - February 12, 2019.
    Present:    Gants, C.J., Gaziano, Lowy, & Budd, JJ.
    Homicide. Proximate Cause. Evidence, Exculpatory, Police
    report, Disclosure of evidence. Deoxyribonucleic Acid.
    Constitutional Law, Fair trial, Confrontation of witnesses.
    Due Process of Law, Fair trial. Fair Trial. Practice,
    Criminal, Capital case, New trial, Discovery, Fair trial,
    Confrontation of witnesses, Disclosure of identity of
    informer.
    Indictments found and returned in the Superior Court
    Department on July 23, 1999.
    The cases were tried before Robert A. Barton, J.; a motion
    for a new trial, filed on May 17, 2002, was heard by Elizabeth
    Butler, J.; and a second motion for a new trial, filed on
    November 20, 2014, was heard by Robert B. Gordon, J.
    Rosemary Curran Scapicchio (Jillise McDonough also present)
    for Anthony Barry.
    Claudia Leis Bolgen for Brian Cahill.
    Casey E. Silvia, Assistant District Attorney (Timothy
    Ferriter, Assistant District Attorney, also present) for the
    Commonwealth.
    1   Four against Anthony Barry and five against Brian Cahill.
    2
    LOWY, J.   Shortly after midnight on April 17, 1999, Kevin
    McCormack and Brian Porreca were part of a group leaving a bar
    in Malden with plans to continue their night at a club in
    Boston.   They never made it.   As the group prepared to leave,
    Porreca saw two longtime friends, Anthony Barry and Brian
    Cahill, run up to the vehicle that the group was entering.
    While Cahill stayed on the passenger side of the vehicle,
    shooting an Uzi at it, Barry fired a handgun into the back of
    McCormack's head as he sat in the driver's seat.    Porreca and
    one of the women in their group were also shot, and Porreca
    retreated into the bar.    Based largely on Porreca's testimony,
    Barry and Cahill were convicted of murder in the first degree.2
    The defendants each filed two motions for a new trial, each
    of which was denied.    Their direct appeal is consolidated with
    their appeal from the denial of those motions, and they argue
    that multiple reversible errors occurred both during and after
    trial.    We consider whether (1) there was sufficient evidence to
    support each defendant's murder conviction; (2) the Commonwealth
    withheld exculpatory evidence in violation of Brady v. Maryland,
    2 Each defendant was also convicted of armed assault with
    intent to murder, G. L. c. 265, § 18 (b); two counts of assault
    and battery by means of a dangerous weapon, G. L. c. 265,
    § 15A (b); and unlawful possession of a firearm, G. L. c. 269,
    § 10 (a).
    3
    
    373 U.S. 83
    (1963); (3) newly discovered evidence warranted a
    new trial; (4) expert testimony regarding deoxyribonucleic acid
    (DNA) violated the defendants' rights to confrontation and due
    process; (5) the defendants' right to a public trial was
    violated; (6) discovery violations implicated the confrontation
    clause; and (7) a motion for the disclosure of a confidential
    informant's identity was erroneously denied.      We affirm.
    Background.   1.   The shooting.    We recite facts that the
    jury could have found and that are necessary to resolve the
    defendants' appeal, reserving some facts for later discussion.
    Porreca met some friends, including McCormack, at a bar in
    Malden on the night of April 16, 1999.      While there, Porreca
    drank four or five beers before he, McCormack, Lindsay Cremone,
    Kristen Terfry, Stephen Almeida, and John Whitson decided to go
    to a club in Boston.    The group left the bar at 12:15 A.M. on
    April 17 and proceeded to Cremone's sister's car.      McCormack sat
    in the driver's seat, Terfry sat in the front passenger seat,
    Cremone sat in the rear driver's side seat, and Porreca was
    preparing to enter the rear seat on the passenger's side3 when he
    heard voices in the parking lot and looked up to see Barry and
    Cahill running in their direction.      The men wore dark hoods that
    covered their ears, hair, and heads, but left their faces
    3 Stephen Almeida had gone back into the bar to get John
    Whitson.
    4
    exposed.   Cahill ran toward the passenger's side of the vehicle
    and fired a nine millimeter Uzi-type semiautomatic weapon into
    it, striking McCormack several times and shooting Porreca and
    Cremone twice each.   Porreca had seen Barry running toward the
    driver's side of the car, and Cremone testified that a man ran
    to the driver's side of the vehicle, put a gun to McCormack's
    head, and shot him.
    After being shot, Porreca observed Cahill turning toward
    the vehicle and heard "a lot of gunshots" as he retreated into
    the bar.   From the back seat, Cremone heard "two different types
    of firing."    As Porreca entered the bar, he yelled "call 9-1-1"
    and approached Whitson, with whom the group had been socializing
    earlier.   Porreca exclaimed, "Fuck'n Barry and Cahill" to
    Whitson, and approached Gene Giangrande's4 girlfriend and told
    her to "[t]ell Gene I'm going to blow his fuck'n head off."
    Porreca explained that he said this because "[i]t was Gene
    Giangrande's crew, his friends who had just shot me, and I was
    mad at him."
    A .40 caliber pistol was found on the ground next to the
    driver's side of the vehicle.   The Uzi used in the attack was
    found by two teenagers walking home at approximately 2:30 A.M.
    4 Gene Giangrande was a local bookmaker and drug dealer for
    whom Brian Porreca collected debts and who was best friends with
    Anthony Barry. Both defendants were part of Giangrande's
    "crew."
    5
    on April 17 on the sidewalk of Whitman Street, close to the bar.
    One of the teenagers who found the Uzi took it home, unloaded
    it, and hid it in the basement of his house before turning it in
    to the Malden police the following day.
    2.   Porreca's background.   Porreca grew up in Medford and
    was friends with each of the defendants.     Porreca introduced the
    defendants to each other in 1994 or 1995, after which the
    defendants became "close."   Porreca was also friends with
    Giangrande, an area bookmaker and drug dealer; William
    Angelesco, a friend of Giangrande's who was known to be
    connected with organized crime; and McCormack, the victim.
    Porreca was a former professional boxer and collected debts owed
    to Giangrande, who would pay him in cash or with Percocet pills.
    Porreca had a lengthy criminal history.     The jury also heard
    evidence of Porreca's substance abuse.     He admitted to being
    addicted to opiates and having consumed two or three Percocet
    pills on the morning of the shooting.
    At the time of the murder, Porreca was under Federal
    investigation for his involvement in the kidnapping of an area
    drug dealer that took place in 1995 (kidnapping).     Allegedly,
    Porreca and another man, in an attempt to determine the location
    of a shipment of marijuana from Mexico, kidnapped the drug
    dealer and brought him to a house in Medford.     The man was tied
    up, sprayed with lighter fluid, and questioned as Porreca held a
    6
    gun and another man held a lighter.    After approximately one
    hour, Porreca and the other man released the kidnapped party.
    In early April 1999, Porreca received a summons to appear before
    a Federal grand jury, and met with several members of law
    enforcement to discuss the likely charges against him.     Porreca
    left that meeting believing that he was facing fifteen or more
    years in prison if he did not cooperate with law enforcement;
    and if he did, his likely sentence would be reduced to
    approximately five years.
    3.   Additional trial evidence.     The jury also heard
    testimony of the police investigation into the shooting.
    Porreca was interviewed by police at the hospital and was
    initially uncooperative.    He first said that "two white guys"
    whom he knew had conducted the shooting, but later stated that
    it was actually "two black guys."     Eventually, Porreca told a
    State police trooper investigating the shooting that he would
    identify the shooters in exchange for a promise that he would
    not go to prison for his involvement in the kidnapping.       Porreca
    received such an assurance from the United States Attorney's
    office, agreed to cooperate, and identified the defendants to
    the police.
    Pursuant to search warrants, police searched Cahill's
    residence in Randolph and recovered an ammunition can with a
    sticker from an army-navy style surplus store in Malden with a
    7
    large pair of Hatch-brand leather gloves.   A search of Barry's
    apartment in Melrose also yielded two Nomex hoods5 and an extra-
    large pair of Hatch gloves in a box with two bulletproof vests.
    The owner of the surplus store testified that two young men
    loosely matching the defendants' descriptions had purchased two
    pairs of Hatch gloves (one large and one extra-large), two Nomex
    hoods, and a can of .30 caliber ammunition one week before the
    shooting.   A DNA expert testified that a saliva sample found on
    one of the Nomex hoods found in Barry's apartment matched
    Cahill's DNA.
    A medical examiner testified about the autopsy he performed
    on McCormack.   Detailing McCormack's injuries, he first
    described the gunshot wound to McCormack's head and offered his
    opinion that that wound alone was lethal.   He further testified
    about a separate, independently lethal gunshot wound to
    McCormack's back.   The bullet removed from McCormack's head was
    a .40 caliber bullet that matched the pistol left on the scene,
    while the second lethal wound was caused by an undetermined, but
    different, caliber bullet.   One .40 caliber shell casing was
    recovered from the crime scene, found in the backseat of the
    car, and fourteen nine millimeter shell casings were found on
    5 Nomex hoods were described as similar to those worn by
    football players or law enforcement in cold weather; they adhere
    tightly to the head but reveal much of the wearer's face,
    including the eyes, nose, and cheeks.
    8
    the scene -- thirteen on or around the car and one on the floor
    of the car.
    4.    First motion for a new trial.   In 2002, approximately
    two years after trial, the defendants filed their first motion
    for a new trial.6    After a three-day evidentiary hearing, the
    motion was denied.7    The primary arguments in the first motion
    centered on evidence discovered after trial that the defendants
    contended would have assisted their attack on Porreca's
    credibility.    They also presented evidence that suggested that
    Giangrande and Angelesco had admitted to others that they,
    rather than the defendants, were the shooters.
    The defendants maintained that the Commonwealth
    intentionally withheld evidence that Porreca was brought by
    police to Saints Memorial Hospital in Lowell on April 21, 1999,
    four days after the shooting, where he complained that he was in
    heroin withdrawal.    In those records, medical staff noted that
    Porreca stated to them to be "drug sick" and that one of the
    police officers accompanying him indicated that he had been
    vomiting for most of the previous night.    At the evidentiary
    hearing, two doctors opined about Porreca's medical records.
    6 We limit our discussion of the decision on the first
    motion for a new trial to the lone portion that the defendants
    assert was erroneous.
    7   The trial judge did not preside over the motion for a new
    trial.
    9
    One of the doctors described the effects of opiate withdrawal
    and indicated that Porreca's behavior at the hospital was
    consistent with being in withdrawal, and that Porreca's actions
    immediately after the shooting were consistent with being
    intoxicated at the time.   In contrast, the doctor who treated
    Porreca testified that, although he did not remember treating
    Porreca, he also did not document any symptoms of withdrawal.
    The treating doctor also testified that the records suggested
    that Porreca was not in withdrawal during the visit.    The judge
    who heard the first motion for a new trial (first motion judge)
    credited the testimony of the doctor who had treated Porreca.
    The defendants contended that the Commonwealth withheld
    these medical records in violation of 
    Brady, 373 U.S. at 87
    ,
    which requires that the Commonwealth disclose to defendants all
    exculpatory evidence in its control.     The first motion judge
    ultimately held that, although the medical records were
    exculpatory and were in the Commonwealth's possession, the
    defendants were not prejudiced by the Commonwealth's failure to
    produce the records because they were cumulative of other
    evidence presented at trial and did not "carry a measure of
    strength in support of the defendant."    Commonwealth v. Bregoli,
    
    431 Mass. 265
    , 272 (2000), quoting Commonwealth v. Tucceri, 
    412 Mass. 401
    , 414 (1992).
    10
    5.     Second motion for a new trial.   The defendants filed a
    second motion for a new trial in November 2014, raising several
    issues, including an argument that the Commonwealth withheld
    newly discovered pieces of exculpatory evidence.      The motion was
    denied following a nonevidentiary hearing, the judge (second
    motion judge)8 having deemed an evidentiary hearing unnecessary
    because the defendants did not raise a serious question under
    Mass. R. Crim. P. 30 (b), as appearing in 
    435 Mass. 1501
    (2001),
    and the briefs, transcripts, and supporting documents were
    sufficient to allow the second motion judge to make an informed
    decision.
    The defendants maintained that police reports discovered
    after trial constituted Brady violations, and that six pieces of
    newly discovered evidence cast doubt on the convictions and
    warranted a new trial.     As the defendants now assert error in
    the denial of this motion for each of these pieces of evidence,
    we briefly detail each piece in turn.
    a.     Orlando reports.   The defendants discovered two reports
    authored after the trial by Sergeant Nunzio Orlando of the State
    police (Orlando reports), one dated July 17, 2001, and the other
    dated July 25, 2001.     The July 17 report was heavily redacted
    8 The judge who decided the second motion for new trial was
    neither the trial judge nor the judge who decided the first
    motion for a new trial.
    11
    and described information gleaned from a confidential informant,
    who stated in part that "Angelesco 'got straightened out'
    because he shot and killed 'Mucka' McCormack in Malden."     The
    July 25 report indicated that Angelesco had become a "made
    member" in the Boston mafia and that he had "'earned his bones'
    by killing 'Mucka' McCormack."     The informant also stated that
    "Anthony Barry was not the shooter in the McCormack murder.
    Barry was behind the scenes as far as orchestrating McCormack's
    assassination, but Angelesco and Cahill were the actual
    shooters.     In addition, Gene Giangrande allegedly drove the
    getaway vehicle."     The second motion judge analyzed these two
    reports under Brady and determined that they were not possessed
    by the Commonwealth, were not exculpatory because they would not
    have been admissible at trial, and were not prejudicial because
    they would not have had an impact on the jury's conclusion.
    b.    Montana report.    A report written by Sergeant David
    Montana of the Medford police department (Montana report)
    relayed a conversation he had with an individual who implicated
    a third party, Robert Rennell, as the shooter in McCormack's
    murder.     This individual further stated that "there was no way
    that Anthony Barry" was the shooter, and that Porreca had
    contacted him indicating that he was willing to alter his
    testimony in exchange for $100,000.     The second motion judge
    concluded that the Montana report had not been possessed by the
    12
    prosecution, was inculpatory despite appearing exculpatory on
    its face because of the fruits of subsequent police
    investigation, and was not prejudicial because it was unlikely
    to have had an impact on the jury's conclusion.
    c.    Bureau of Alcohol, Tobacco, Firearms and Explosives
    report.   The final asserted Brady violation raised in the second
    motion for a new trial concerned an unredacted version of a
    report from the Bureau of Alcohol, Tobacco, Firearms and
    Explosives (ATF report) detailing an interview of Porreca
    conducted on April 21, 1999.   In the redacted version of the
    report, which the defense possessed at the time of trial,
    Porreca stated that he had spoken to a friend of McCormack,
    Johnnie Decologero, at the bar on the night of the shooting and
    that Barry did not get along with Decologero's brother, Paul.
    The unredacted version indicated, among other things, that Paul
    Decologero had initiated the 1995 kidnapping for which Porreca
    was under Federal investigation in 1999.
    The second motion judge determined that neither version of
    the ATF report was exculpatory, particularly because even the
    redacted version named the defendants as the shooters.     He
    further concluded that the defendants had not established that
    the unredacted version of the report, created by a Federal
    agency, was ever in the possession of the Commonwealth.
    Finally, the judge determined that the defendants did not
    13
    establish that they were prejudiced by not possessing the
    unredacted ATF report.
    d.     Newly discovered evidence.   The second motion judge
    also considered the defendants' argument that six pieces of
    newly discovered evidence would have had an impact on the jury's
    verdicts.    Those pieces of evidence include a third report
    authored by Orlando on July 26, 2001,9 additional evidence of
    Porreca's drug use, an affidavit from Whitson, an affidavit from
    Brittany Cahill, evidence that Angelesco had committed a
    different murder, and evidence that police intimidated potential
    witnesses prior to the hearing on the first motion for a new
    trial.    The motion was denied, and the judge reached the
    following conclusions:     (1) the absence of the July 26 Orlando
    report did not undermine the denial of the first motion for a
    new trial; (2) the evidence regarding Porreca's drug use was
    cumulative, not newly discovered, and insufficient to warrant a
    new trial as it went merely to credibility; (3) Whitson's
    affidavit, which contradicted Porreca's testimony that he had
    cursed Barry's and Cahill's names to Whitson after retreating
    into the bar following the shooting, was reasonably discoverable
    9 The only evidence in the July 26 Orlando report that was
    not included in the first two Orlando reports was a discussion
    of a dispute at a strip club in Rhode Island where Angelesco
    allegedly attempted to calm the situation by telling a Rhode
    Island man involved in the same organized crime syndicate that
    they were "with the same people."
    14
    at the time of trial and cumulative of other testimony
    undercutting Porreca's recollection; (4) Brittany Cahill's
    affidavit, in which she recanted portions of her testimony
    against her brother, was inconsequential to the jury's verdicts;
    (5)    evidence that Angelesco was indicted for and acquitted of a
    different murder with loose factual similarities to McCormack's
    death would not have been admissible at the defendants' trial as
    evidence of a third-party culprit; and (6) the defendants'
    argument that law enforcement targeted potential witnesses with
    search and arrest warrants to discourage them from testifying at
    the hearing on the first motion for a new trial was meritless
    because the actions of the police were the result of a long
    investigation.
    e.   DNA expert.   The defendants' second motion for a new
    trial also challenged the DNA testimony at trial, asserting that
    their constitutional right to confrontation had been violated
    because the DNA expert had not conducted the testing.     The
    second motion judge determined that the expert, who was the
    director of the laboratory where the DNA was analyzed, discussed
    his laboratory's procedures and then opined that the DNA found
    in saliva on the Nomex hood was a near certain match to Cahill's
    DNA.    The judge held that, because the expert was referring to
    his own conclusions based on a report that he was involved in
    creating, he was not a substitute expert and the defendants'
    15
    right to confrontation was not implicated.   The judge further
    concluded that the defendants' challenge to the reliability of
    the DNA testing itself, which was based on testing of only eight
    DNA loci, was unfounded.   The judge noted the expert's testimony
    that using eight loci was an accepted method in the scientific
    community and observed that the defendants failed to establish
    that the method was unreliable.
    f.    Court room closure.   The defendants asserted that the
    trial judge's practice of conducting a hardship inquiry of
    jurors outside the presence of the defendants and their counsel,
    as well as the exclusion of members of the defendants' families
    during jury selection, constituted constitutional violations
    warranting a new trial.    The second motion judge concluded that
    the hardship inquiry was not a critical stage of the proceedings
    and therefore did not implicate the defendants' constitutional
    rights.   Additionally, the judge found that the argument
    regarding the exclusion of family members from jury selection
    was waived because it had neither been preserved at trial nor
    raised in the first motion for a new trial, and that the
    defendants failed to establish that it created a substantial
    risk of a miscarriage of justice.
    Discussion.    The defendants' appeals from the denial of
    their motions for a new trial have been consolidated with their
    direct appeals from their convictions of murder in the first
    16
    degree.   We review both under G. L. c. 278, § 33E, and consider
    asserted errors in the motions for a new trial "to determine
    whether there has been a significant error of law or other abuse
    of discretion, . . . and whether any such error creates a
    substantial likelihood of a miscarriage of justice."
    Commonwealth v. Vargas, 
    475 Mass. 338
    , 355 (2016), quoting
    Commonwealth v. Lally, 
    473 Mass. 693
    , 698 (2016).
    1.   Sufficiency of the evidence.   The defendants maintain
    that the evidence presented at trial was insufficient to
    establish which gunshot wound was fatal, and that the trial
    judge's denial of their motions for a required finding of not
    guilty was therefore error because they were both tried as
    principals rather than on a joint venture theory.10    We review
    the denial of a motion for a required finding of not guilty to
    determine "whether the evidence offered by the Commonwealth,
    together with reasonable inferences therefrom, when viewed in
    its light most favorable to the Commonwealth, was sufficient to
    persuade a rational jury beyond a reasonable doubt of the
    existence of every element of the crime charged."     Commonwealth
    v. Whitaker, 
    460 Mass. 409
    , 416 (2011), quoting Commonwealth v.
    Lao, 
    443 Mass. 770
    , 779 (2005), S.C., 
    450 Mass. 215
    (2007) and
    10The defendants' trial took place before this court's
    decision in Commonwealth v. Zanetti, 
    454 Mass. 449
    (2009), which
    the Commonwealth notes changed its practice in pursuing a theory
    of joint venture liability in cases like this.
    17
    
    460 Mass. 12
    (2011).   See Commonwealth v. Latimore, 
    378 Mass. 671
    , 677-678 (1979).
    The defendants challenge only the Commonwealth's proof of
    causation.   "It is well established that there may be more than
    one proximate cause of a victim's death."   Commonwealth v.
    Maynard, 
    436 Mass. 558
    , 563 (2002).   The conduct of two or more
    persons is each a proximate cause of death if the conduct
    concurrently contributes to the death.   
    Id. at 564.
      Such "[a]
    cause is concurrent if it was operative at the moment of death
    and acted with another cause to produce the death."    
    Id. We conclude
    that the evidence and the reasonable inferences
    that stem from it, when considered in the light most favorable
    to the Commonwealth, were sufficient to convict both defendants.
    The medical examiner determined that two separate gunshot
    wounds, one to the head and one to the back, were each "in and
    of [themselves] lethal."   The medical examiner noted McCormack's
    cause of death as "multiple gunshot wounds."   The two gunshots
    were fired from two different weapons.   The gunshot to the head
    was from a .40 caliber firearm.   The gunshot to the back was
    from a different firearm of an undetermined caliber.   The
    witness described the two defendants as the only two shooters.
    We find support in several past decisions of this court.
    The Maynard case and Commonwealth v. Perry, 
    432 Mass. 214
    (2000), involved a victim who was subjected to numerous blunt
    18
    force injuries and starvation over several months by the
    respective defendants.     
    Maynard, 436 Mass. at 559-561
    .        
    Perry, 432 Mass. at 215-219
    .    In those cases, which each considered the
    same murder, the medical examiner testified that he could not
    determine which act was fatal, but that "the cumulative effect
    of the beatings and starvation led to the victim's death."
    Perry, supra at 220-221.    See Maynard, supra at 563.      We
    concluded that there was sufficient evidence to convict the
    defendants under both principal and joint venture theories of
    liability.   
    Id. at 565.
       Perry, supra at 221.   In this case, the
    evidence that the defendants caused McCormack's death is much
    stronger than it was in the Perry and Maynard cases.        The
    judge's denial of the defendants' motion for a required finding
    of not guilty was proper.
    2.   First motion for a new trial.     The defendants maintain
    that the Commonwealth intentionally withheld hospital records
    from a visit Porreca made to Saints Memorial Hospital on April
    21, 1999.    Porreca complained that he was in heroin withdrawal
    and requested methadone, and the defendants argue that the
    temporal proximity of this withdrawal to the shooting would have
    undermined Porreca's testimony that he was not influenced by
    drugs at the time of the shooting.    This, the defendants
    contend, prejudiced their defense in such a way that their first
    motion for a new trial should have been allowed.
    19
    "Evidence is exculpatory if it 'provides some significant
    aid to the defendant's case, whether it furnishes corroboration
    of the defendant's story, calls into question a material,
    although not indispensable, element of the prosecution's version
    of the events, or challenges the credibility of a key
    prosecution witness.'"   Commonwealth v. Watkins, 
    473 Mass. 222
    ,
    231 (2015), quoting Commonwealth v. Daniels, 
    445 Mass. 392
    , 401-
    402 (2005).   "To obtain a new trial on the basis of nondisclosed
    exculpatory evidence, a defendant must establish (1) that 'the
    evidence [was] in the possession, custody, or control of the
    prosecutor or a person subject to the prosecutor's control'; (2)
    'that the evidence is exculpatory'; and (3) 'prejudice.'"
    Commonwealth v. Sullivan, 
    478 Mass. 369
    , 380 (2017), quoting
    Commonwealth v. Murray, 
    461 Mass. 10
    , 19, 21 (2011).    The first
    motion judge determined, and we agree, that the defense did not
    make a specific discovery request that encompassed Porreca's
    medical records.11   Where no specific request for a particular
    11The defendants maintain that we should depart from the
    first motion judge's determination and conclude that one portion
    of their 1999 discovery motion should be considered a specific
    request for documents including records of Porreca's visit to
    Saints Memorial Hospital on April 21. That request was made as
    follows: "Any material relating to the witness' mental or
    physical history that tends to impair or reflect adversely on
    his reliability as a witness, including but not limited to any
    information that would tend to affect the witness' motive to
    testify or ability to perceive, recall, or understand events."
    The defendants' discovery motion was amended, and the section in
    question was edited to state: "Any material [that] would tend
    20
    piece of evidence is made, we determine prejudice using the same
    standard "used to assess the impact of newly discovered
    evidence, that is, 'whether there is a substantial risk that the
    jury would have reached a different conclusion if the evidence
    had been admitted at trial.'"   Murray, supra at 21, quoting
    Commonwealth v. Tucceri, 
    412 Mass. 401
    , 413 (1992).   "Newly
    discovered evidence that tends merely to impeach the credibility
    of a witness will not ordinarily be the basis of a new trial."
    Sullivan, supra at 383, quoting Commonwealth v. Lo, 
    428 Mass. 45
    , 53 (1998).
    Because we agree with the first motion judge that there is
    no substantial risk of an impact on the verdicts had evidence of
    Porreca's trip to Saints Memorial Hospital been before the jury,
    we need not address the other two factors underlying a new trial
    motion on the basis of nondisclosed exculpatory evidence.   See
    
    Sullivan, 478 Mass. at 380
    .   Porreca was extensively cross-
    examined over the course of two days, during which he admitted
    that he was addicted to opiates, had often been paid in Percocet
    to affect the witness' motive to testify or ability to perceive,
    recall, or understand events." We agree with the judge that
    Porreca's medical records were not specifically requested, in
    either the original or amended motion, as a specific request
    puts the prosecutor on "notice of exactly what the defense
    desired." United States v. Agurs, 
    427 U.S. 97
    , 106 (1976). Cf.
    Commonwealth v. Healy, 
    438 Mass. 672
    , 680 n.9 (2003)
    (defendant's request for "'reports of mental or physical
    examinations and of scientific tests' qualifies as a 'specific
    request'" for "postmortem report").
    21
    pills by Giangrande, had consumed two or three Percocet pills on
    the day of the shooting, and had consumed five or six beers
    while at the bar immediately before the shooting.   He denied
    having been under the influence, at the time of the shooting, of
    the Percocet pills that he had consumed earlier in the day,
    reasoning that he had consumed only two or three pills and that
    he would have needed to consume approximately five pills to feel
    any effect "because [his] system had been used to them."
    Porreca also testified that he had been given Percocet while in
    the hospital after the shooting, and was prescribed an
    additional ten Percocet pills on his discharge from the hospital
    on April 19.
    Given this testimony, the exculpatory nature of the
    evidence of Porreca's complaint of heroin withdrawal four days
    after the shooting was cumulative of evidence already before the
    jury, and we are not persuaded that it would have had an impact
    on the jury's verdicts.   Porreca's drug use was well
    established, and he admitted that he consumed Percocet pills and
    drank several beers on the day of the shooting.   His credibility
    was called into question extensively on cross-examination on
    several grounds, not limited to his drug use, and the jury
    nonetheless convicted the defendants.   See Commonwealth v.
    Dubois, 
    451 Mass. 20
    , 28 (2008) ("The weight and credibility of
    the evidence is the province of the jury").   The Saints Memorial
    22
    Hospital records, at most, would have provided additional
    grounds to impeach Porreca on the truthfulness of his testimony
    regarding his sobriety on the night of the shooting.
    Commonwealth v. Lykus, 
    451 Mass. 310
    , 326 (2008) (evidence
    cumulative of that "admitted at the trial will carry little
    weight").   See 
    Sullivan, 478 Mass. at 380
    .   Had those records
    been available to the defense, there would not have been an
    impact on the jury's verdicts.
    3.   Second motion for a new trial.    The defendants raise
    several arguments stemming from the denial of their second
    motion for a new trial.   We address each in turn.
    a.   Decision not to hold evidentiary hearing.     We first
    address the defendants' contention that the second motion
    judge's decision to proceed without an evidentiary hearing was
    error.   We disagree.   Under Mass. R. Crim. P. 30 (c) (3), as
    appearing in 
    435 Mass. 1501
    (2001), a judge must determine
    whether the defendants' motion presents a "substantial issue" in
    deciding whether an evidentiary hearing is necessary.
    Commonwealth v. Denis, 
    442 Mass. 617
    , 628 (2004).     "Although the
    motions and supporting materials filed by a defendant need not
    prove the issue raised therein, they must at least contain
    sufficient credible information to cast doubt on the issue" in
    order to create a substantial issue.    
    Id. at 629.
      In
    determining whether a substantial issue exists, "a judge
    23
    considers the seriousness of the issues raised and the adequacy
    of the defendant's showing on those issues."     Commonwealth v.
    Torres, 
    469 Mass. 398
    , 402-403 (2014).     Whether to hold an
    evidentiary hearing is a decision squarely within the judge's
    discretion, and we review the decision for an abuse of
    discretion.   Denis, supra at 628.
    The second motion judge determined that an evidentiary
    hearing was unnecessary because the defendants did not raise a
    serious question and because the briefs, supporting documents,
    and trial transcripts were sufficient to allow him to reach an
    informed decision.    We conclude that the record before the judge
    and the contents of the reports and affidavits that formed the
    basis for the legal arguments raised in the second motion for a
    new trial did not require an evidentiary hearing, and that the
    judge's decision that an evidentiary hearing was not warranted
    was a proper exercise of his discretion.    See Commonwealth v.
    McWilliams, 
    473 Mass. 606
    , 622-623 (2016).
    b.   Police reports.    We next address the defendants'
    argument that the judge erred in declining to find a Brady
    violation.    The defendants, having discovered additional law
    enforcement reports after their first motion for a new trial had
    been decided, presented three claimed new Brady violations based
    on those reports.    The judge did not err in concluding that
    there were no Brady violations.
    24
    i.   Montana report.     The Montana report detailed an
    interview conducted by a member of the Medford police department
    during which an individual implicated a third party as the
    shooter in McCormack's murder, indicated that "there was no way"
    that Barry was the shooter, and stated that Porreca had told the
    individual that he was willing to change his testimony in
    exchange for $100,000.     As there was no specific discovery
    request that encompassed this report, we analyze any error to
    determine "whether there is a substantial risk that the jury
    would have reached a different conclusion if the evidence had
    been admitted at trial."     
    Murray, 461 Mass. at 21
    , quoting
    
    Tucceri, 412 Mass. at 413
    .    Assuming without deciding that the
    Montana report satisfies the first two prongs of Brady, we
    conclude that there was no prejudice because the defendants
    cannot establish that the Montana report creates a substantial
    risk that the jury would have reached a different conclusion had
    it been admitted.   See Murray, supra at 19-21.
    The Montana report implicates a potential third-party
    culprit who had not otherwise been considered in the
    investigation.   However, the report does not indicate the basis
    for the statement that Barry could not have been the shooter.
    See 
    Tucceri, 412 Mass. at 414
    (if evidence "does not carry a
    measure of strength in support of the defendant, the failure to
    disclose that evidence does not warrant the granting of a new
    25
    trial").   Finally, to the extent that evidence of Porreca's
    willingness to alter his testimony in exchange for money could
    have been used to impeach his credibility, "evidence that tends
    merely to impeach the credibility of a witness will not
    ordinarily be the basis of a new trial."   
    Sullivan, 478 Mass. at 383
    , quoting 
    Lo, 428 Mass. at 53
    .   Moreover, any additional
    impeachment evidence, unsupported by details and uncorroborated
    by additional evidence, would not have influenced the jury's
    conclusion because Porreca's credibility was already very much
    called into question on cross-examination.   We therefore
    conclude that there was no prejudice.
    We further note that the individual who provided the
    information in the Montana report wrote an affidavit that
    undermines the exculpatory nature of the Montana report and led
    to an investigation that further inculpates the defendants.
    That person stated that he did not remember telling Sergeant
    Montana that Rennell shot McCormack or that Porreca stated that
    he was willing to change his story and that neither of those
    things is true.   He further discussed his relationship with an
    area drug dealer who had tried to sell him stolen guns from New
    Hampshire, and eventually sold Barry a .40 caliber pistol.     The
    pistol left at the scene of the shooting that was used to shoot
    McCormack in the head was confirmed to be a gun that had been
    stolen from a person in Derry, New Hampshire.
    26
    A motion for a new trial may be granted "if it appears that
    justice may not have been done."    Mass. R. Crim. P. 30 (b).     The
    exculpatory nature of the Montana report has since been recanted
    and prompted police investigation that directly tied Barry to
    one of the murder weapons.    As we are considering whether
    substantial justice was done, we see no reason that we cannot
    consider additional evidence that stemmed from that police
    investigation.12   With the fruits of that investigation in mind,
    any argument that this report would warrant a new trial in the
    interests of justice is disingenuous.
    ii.   ATF report.   The defendants' asserted Brady violation
    stemming from the unredacted ATF report also fails, because the
    ATF report was not exculpatory.    The report's only mention of
    McCormack's murder is that Porreca stated, "Anthony Barry, one
    of the shooters along with Brian Cahill, didn't get along with
    Paul A. Decologero."     The defendants, however, maintain that
    Porreca's cooperation with law enforcement and the ATF report's
    12The defendants contend that the second motion judge
    violated their right to due process by relying on evidence that
    the Commonwealth obtained after the defendants' convictions.
    The Montana report led police to discover, among other things,
    evidence that Barry had purchased the .40 caliber pistol that
    was left in the bar's parking lot and matched the bullet
    recovered from McCormack's skull. Because we have concluded,
    without considering that evidence, that there was no Brady
    violation stemming from the Montana report, any error by the
    judge in relying on later discovered evidence implicating Barry
    would be harmless. See Commonwealth v. Amirault, 
    424 Mass. 618
    ,
    649 (1997).
    27
    discussion of the involvement of Decologero in the kidnapping
    provide for the possibility of a third-party defense, because
    the ATF report could arguably indicate that Decologero had
    motive to kill Porreca.   But the ATF report inculpates the
    defendants by saying that they were the shooters.    Any motive
    that could be gleaned from the ATF report would not be a
    significant enough aid to the defense to be deemed exculpatory.
    iii.   Orlando reports.   Lastly, we address the three
    Orlando reports.   Although the second motion judge treated the
    July 26, 2001, Orlando report as newly discovered evidence and
    reviewed the July 17 and July 25 reports under Brady, we review
    all three Orlando reports as newly discovered evidence because
    they were all created after trial.    "A defendant seeking a new
    trial on the ground of newly discovered evidence must establish
    both that the evidence is newly discovered and that it casts
    real doubt on the justice of the conviction."    Commonwealth v.
    Grace, 
    397 Mass. 303
    , 305 (1986).    As a threshold matter, newly
    discovered evidence "must be material and credible."    
    Id. We conclude
    that the contents of the Orlando reports are not
    credible and therefore cast no doubt on the convictions.
    The confidential informant in the Orlando reports told
    Trooper Orlando that he did not have firsthand knowledge of who
    the shooters were, that he was not present at the time of the
    murder, and that his information that Angelesco was the shooter
    28
    and Giangrande the getaway driver was based on "word on the
    street."     "'[W]ord on the street' carries no indicia of
    reliability by itself, and defense counsel did not bolster it by
    showing that the 'word' came from a percipient witness to the
    shooting."    Commonwealth v. Silva-Santiago, 
    453 Mass. 782
    , 804-
    805 (2009).13    Because unsubstantiated rumors pointing to
    Angelesco and Giangrande as the true culprits do not cast doubt
    on the justice of the convictions, the existence of the Orlando
    reports does not require a new trial.
    c.    Additional newly discovered evidence.   In their second
    motion for a new trial, the defendants also relied on five
    additional pieces of purportedly newly discovered evidence:     (1)
    additional evidence of Porreca's drug use14; (2) an affidavit
    from Whitson; (3) an affidavit from Brittany Cahill; (4)
    evidence that Angelesco had committed a different murder; and
    (5) evidence of intimidation of potential witnesses before the
    hearing on the first motion for a new trial.     Evidence is newly
    discovered if it was "unknown to the defendant or his counsel
    13The standard articulated in Commonwealth v. Silva-
    Santiago, 
    453 Mass. 782
    (2009), regarding the standard of
    admissibility for evidence offered in support of a defense under
    Commonwealth v. Bowden, 
    379 Mass. 472
    , 485-486 (1980), was
    recently clarified in Commonwealth v. Moore, 
    480 Mass. 799
    , 809
    n.9 (2018). Otherwise, the Silva-Santiago decision remains
    binding.
    14The defendants do not contest the second motion judge's
    ruling relating to Porreca's intoxication.
    29
    and not reasonably discoverable by them at the time of trial (or
    at the time of the presentation of an earlier motion for a new
    trial)."   
    Grace, 397 Mass. at 306
    .   Newly discovered evidence
    "must [also] carry a measure of strength in support of the
    defendant's position," and will carry less weight if it "is
    cumulative of evidence admitted at the trial."     
    Id. at 305-306.
    i.     Whitson affidavit.   Whitson's affidavit indicates that
    he was inside the bar when the shooting took place outside, that
    he spoke to Porreca after Porreca had been shot, and that
    Porreca "did not mention the names of Anthony Barry and Brian
    Cahill" to him.   Whitson's affidavit directly contradicts a key
    portion of Porreca's testimony at trial, where Porreca stated
    that he ran into the bar after being shot and said "Fuck'n Barry
    and Cahill" to Whitson.    However, the defendants have failed to
    establish that the contents of Whitson's affidavit were unknown
    to their counsel at the time of trial.     When Porreca was about
    to testify that he had implicated the defendants to Whitson
    after being shot, Barry's counsel was heard at a sidebar
    conference.   Counsel told the trial judge that "Whitson was
    interviewed by the grand jury and by police, he has denied that
    this statement was made . . . by Porreca to him."     Because
    defense counsel knew before trial that Whitson had said Porreca
    never implicated the defendants, Whitson's affidavit is not
    "newly discovered."   See 
    Grace, 397 Mass. at 306
    .
    30
    ii.    Brittany Cahill affidavit.    Brittany Cahill testified
    against her brother and Barry at trial when she was fourteen
    years old.     Her testimony indicated that Cahill and Barry
    planned to be together the night of the shooting, that Cahill
    laughed when reading a newspaper article about the shooting,
    that Cahill talked to himself while laughing as he drove by the
    bar three days after the shooting, that Cahill was counting $900
    in cash three days after the shooting at a time in which he was
    unemployed, and that Cahill told her, in a telephone call from
    jail several weeks after the shooting, not to give information
    to the police.
    Her 2009 affidavit recanted portions of her testimony, in
    particular denying that Cahill had laughed while reading the
    newspaper, that he had laughed and talked to himself while
    driving past the bar, or that he had stated that the $900 he was
    counting was from "doing his business."     She further indicated
    that her false testimony was the result of pressure from Trooper
    Manning, whom she claims said to her, among other things, that
    she would get in trouble if she did not testify against her
    brother.     Assuming without deciding that Brittany Cahill's
    affidavit constitutes newly discovered evidence, her recantation
    is ultimately inconsequential to the outcome of the trial.
    There was significant evidence pointing to the defendants as the
    shooters, and although Brittany Cahill's testimony did have some
    31
    corroborative value to the Commonwealth's case, "the absence of
    [her recanted] testimony at trial would not have changed the
    verdict[s]."   Commonwealth v. Spray, 
    467 Mass. 456
    , 472 (2014).
    See 
    Grace, 397 Mass. at 306
    ("The strength of the case against a
    criminal defendant . . . may weaken the effect of [newly
    discovered] evidence").
    iii.    Evidence that Angelesco committed a different murder.
    The defendants next contend that they were entitled to a new
    trial because of evidence that Angelesco was indicted for a
    different murder that had similar facts to McCormack's murder.
    In that unrelated murder, of which Angelesco was acquitted, a
    gun was left at the scene, as was the case in McCormack's
    murder.    Evidence of this separate murder is irrelevant to any
    third-party culprit defense the defendants may have raised at
    trial and would not have been admissible.    "[I]n order to be
    admitted, third-party culprit evidence 'must have a rational
    tendency to prove the issue the defense raises, and [it] cannot
    be too remote or speculative.'"    Commonwealth v. Scott, 
    470 Mass. 320
    , 327 (2014), quoting 
    Silva-Santiago, 453 Mass. at 801
    .
    See Commonwealth v. Brusgulis, 
    406 Mass. 501
    , 506 (1990) (modus
    operandi evidence only admissible if there is "a uniqueness of
    technique, a distinctiveness, or a particularly distinguishing
    pattern of conduct common to the current and former incidents").
    This evidence does not warrant a new trial.
    32
    iv.   Witness intimidation.    The defendants' final argument
    from their second motion for a new trial stems from their first
    motion for a new trial, as they allege that members of the State
    police intimidated five witnesses the defendants intended to
    call at the hearing on the first motion by executing search and
    arrest warrants against them.      There is nothing in the record to
    suggest that those warrants were illegitimate, and the arrest
    reports note that they were the product of a "lengthy
    investigation."   The criminal complaints against these five
    potential witnesses detail ongoing narcotics activity, and the
    defendants have provided no evidence to support their claims
    that law enforcement used these arrests as a means to dissuade
    the potential witnesses from testifying at the hearing on the
    first motion for a new trial.15     The burden was on the defendants
    to prove the facts underlying their motion; as they failed to do
    so regarding their witness intimidation claim, their argument
    regarding the second motion for a new trial fails.      See
    Commonwealth v. Marinho, 
    464 Mass. 115
    , 123 (2013) ("A defendant
    bears the burden of proof on a motion for new trial").
    v.    Court room closure.   Cahill maintains that his right to
    a public trial was violated when the trial judge conducted the
    hardship voir dire in the jury room without counsel or
    15One of the men did, in fact, testify at the hearing on
    the first motion for a new trial.
    33
    defendants present, and when the defendants' family members were
    excluded from the court room during jury selection.     Because
    Cahill failed to object to either alleged error at trial, the
    claims are procedurally waived.     See Commonwealth v. Robinson,
    
    480 Mass. 146
    , 152 (2018) ("where a defendant fails to
    contemporaneously object to an improper court room closure at
    trial, we have steadfastly held that the defendant's claim is
    procedurally waived").16     Therefore, we review any error for a
    substantial likelihood of a miscarriage of justice, and having
    found nothing that calls into question the legitimacy of the
    jury's verdicts, we conclude that the defendants' motion for a
    new trial was properly denied on these grounds.      See 
    id. at 154-
    155.
    vi.   DNA.   The defendants challenge the second motion
    judge's determination that the DNA expert who testified at trial
    Cahill urges us to revisit our waiver rules in light of
    16
    the United States Supreme Court's decision in Weaver v.
    Massachusetts, 
    137 S. Ct. 1899
    (2017). He argues that, under
    Weaver, a failure to make a public trial objection at trial
    constitutes waiver only for defendants who raise the issue for
    the first time on appeal as part of an ineffective assistance
    claim rather than as a public trial claim. But in Commonwealth
    v. Robinson, 
    480 Mass. 146
    , 154 (2018), a case decided after
    Weaver, we observed that this is a distinction without a
    difference: "For purposes of determining whether the
    defendant's claim was properly preserved at trial, it is . . .
    legally irrelevant that [the defendant] now presents the claim
    as a Sixth Amendment violation rather than a claim that his
    counsel provided ineffective assistance by failing to perceive
    and object to the closure."
    34
    was not a substitute expert and that their claim that the method
    of testing was unreliable was unfounded.    The defendants did not
    object to the DNA expert's testimony at trial, so we review
    their claim to determine whether there was error in allowing him
    to testify and, if so, whether that error created a substantial
    likelihood of a miscarriage of justice.    We conclude that there
    was no error.
    The expert was the director and vice-president of the
    laboratory where the testing took place, he detailed the
    procedure that would have taken place to test the samples, and
    he testified that, after reviewing the DNA samples, he had
    determined that the DNA found on the Nomex hood matched Cahill's
    DNA profile.    He observed that "the probability of drawing at
    random a DNA pattern like that of Mr. Cahill's is one in [181]
    billion [among Caucasians]."
    "The critical issue with respect to an expert, including in
    particular a DNA analyst, is whether the defendant is able to
    cross-examine the expert in a meaningful way regarding possible
    flaws relating to the underlying data that forms the basis of
    his or her opinion."    Commonwealth v. Chappell, 
    473 Mass. 191
    ,
    201 (2015).    The defendants' rights were protected in this case,
    because the DNA expert participated in the analysis of the
    samples and testified about a report detailing his conclusions
    that he personally submitted to the prosecution.    He was not a
    35
    substitute expert, and his testimony did not implicate the
    confrontation clause.   See Bullcoming v. New Mexico, 
    564 U.S. 647
    , 652 (2011) ("The accused's right is to be confronted with
    the analyst who made the certification . . .").   Cf.
    Commonwealth v. Tassone, 
    468 Mass. 391
    , 399 (2014) ("our common
    law of evidence requires that the defendant have a meaningful
    opportunity to cross-examine the expert about her opinion and
    the reliability of the facts or data that underlie her
    opinion").   Even if he were considered a substitute expert, his
    testimony would have been admissible because there is no
    requirement that the person who physically tested DNA samples
    testify, and it is well established that an expert can testify
    to his own opinions after interpreting data and reaching his own
    conclusions.   See Commonwealth v. Sanchez, 
    476 Mass. 725
    , 733
    (2017); Commonwealth v. Greineder, 
    464 Mass. 580
    , 601-602, cert.
    denied, 
    571 U.S. 865
    (2013); Commonwealth v. Barbosa, 
    457 Mass. 773
    , 791 (2010), cert. denied, 
    563 U.S. 990
    (2011).     Cf.
    Chappell, supra at 202 ("under Massachusetts law, an expert
    witness is not permitted to testify on direct examination to
    facts or data that another, nontestifying expert has generated,
    or to the nontestifying expert's own opinion, even though this
    information may be an important part of the basis of the
    testifying expert's opinion").
    36
    The defendants further assert that the DNA testing, which
    compared Cahill's blood sample and the DNA sample from the Nomex
    hood using eight loci, was unreliable when considered in light
    of subsequent scientific advancements.    The defendants contend
    that because testing involving thirteen loci would "offer[] a
    material improvement in accuracy," there was a substantial
    likelihood of a miscarriage of justice.   See Commonwealth v.
    Donald, 
    468 Mass. 37
    , 45-46 (2014) (analysis using thirteen loci
    reduced probability of random match to one in several trillion
    or quadrillion).   However, the defendants have not called into
    question the legitimacy of the expert's conclusion that the
    probability of a random match was one in 181 billion.       That
    another method of testing may have yielded an even more reliable
    result does not create a substantial likelihood of a miscarriage
    of justice.
    vii.   Pretrial disclosure and the confrontation clause.
    The defendants asserted in their second motion for a new trial
    that the failure to turn over medical evidence regarding
    Porreca's drug use violated their right to confrontation.          The
    second motion judge gave little credence to this argument,
    because it is well established that the right to confrontation
    is a trial right and is inapplicable to pretrial discovery under
    both art. 12 of the Massachusetts Declaration of Rights and the
    Sixth Amendment to the United States Constitution.    See
    37
    Commonwealth v. Figueroa, 
    79 Mass. App. Ct. 389
    , 400 (2011),
    quoting Pennsylvania v. Ritchie, 
    480 U.S. 39
    , 53 (1987).      The
    defendants now ask us to depart from precedent and extend the
    right to confrontation.    We decline to do so.
    "[T]he principal evil at which the Confrontation Clause was
    directed was the civil-law mode of criminal procedure, and
    particularly its use of ex parte examinations as evidence
    against the accused."     Crawford v. Washington, 
    541 U.S. 36
    , 50
    (2004).   "A witness's testimony against a defendant is thus
    inadmissible unless the witness appears at trial or, if the
    witness is unavailable, the defendant had a prior opportunity
    for cross-examination."    Melendez-Diaz v. Massachusetts, 
    557 U.S. 305
    , 309 (2009), citing Crawford, supra at 54.     The right
    to confrontation, under both art. 12 and the Sixth Amendment,
    has been considered to be a trial right.    Figueroa, 79 Mass.
    App. Ct. at 400.   There was no error in the second motion
    judge's treatment of the right to confrontation as such, and we
    conclude that there is no reason to depart from that
    interpretation.
    4.    Identity of confidential informant.     In December 2015,
    the defendants filed a discovery motion seeking, in part, the
    disclosure of the identity of the confidential informant
    discussed in the Orlando reports.    The motion was denied.    The
    second motion judge determined that the Commonwealth had
    38
    established that disclosing the informant's identity would
    endanger the informant, and that the defendant failed to show
    that the "informant privilege" interfered with a fair defense.
    The defendants now contend that the judge erred in denying the
    motion.   We conclude that there was no error.
    The defendants contend that the Orlando reports indicate
    that the confidential informant had firsthand knowledge that
    Angelesco, not the defendants, murdered McCormack, and that
    Giangrande "drove the getaway vehicle."    As 
    discussed supra
    , the
    Commonwealth filed an affidavit by Sergeant Orlando clarifying
    that the confidential informant did not have firsthand
    knowledge, was not a percipient witness, and did not hear the
    information from Angelesco or Giangrande, but rather learned it
    through "word on the street."    The Commonwealth withheld the
    confidential informant's identity under the "informant
    privilege."    The informant privilege "may be asserted where the
    Commonwealth otherwise would be required to provide an
    informant's identity to a defendant as part of its discovery
    obligations."17   Commonwealth v. Bonnett, 
    472 Mass. 827
    , 846
    (2015).   The privilege's rationale "is the need to encourage
    'citizens to communicate their knowledge of the commission of
    17There   is apparently no disagreement that, absent
    assertion of   the informant privilege, the identity of the
    confidential   informant would be discoverable under Mass. R.
    Crim. P. 14,   as appearing in 
    442 Mass. 1518
    (2004).
    39
    crimes to law-enforcement officials.'"    
    Id., quoting Roviaro
    v.
    United States, 
    353 U.S. 53
    , 59 (1957).
    Determining whether an informant's identity was properly
    withheld requires a two-step inquiry.    In the first stage, we
    must determine "(a) whether the Commonwealth has properly
    asserted an informant privilege, and (b) whether the defendant
    has adequately challenged the assertion of the privilege as an
    impermissible interference with his or her right to present a
    defense."   
    Bonnett, 472 Mass. at 846
    .   The Commonwealth may
    assert the privilege only where "disclosure would endanger the
    informant or otherwise impede law enforcement efforts."     
    Id. at 847.
      If the Commonwealth has properly asserted the privilege,
    "the defendant may request that the privilege be set aside on
    the grounds that it 'interferes with a fair defence.'"    
    Id., quoting Commonwealth
    v. Johnson, 
    365 Mass. 534
    , 544 (1974).       In
    so requesting, a defendant must "present 'some offering so that
    the trial judge may assess the materiality and relevancy of the
    disclosure to the defense,'" but only if it "is not apparent
    from the nature of the case and the defense offered thereto."
    
    Bonnett, supra
    , quoting Commonwealth v. Kelsey, 
    464 Mass. 315
    ,
    323 (2013).
    If the Commonwealth properly invoked the privilege and the
    defendants adequately challenged the assertion of the privilege,
    then we move to the second step and balance "the public interest
    40
    in protecting the flow of information against the [defendant]'s
    right to prepare his defense."   Commonwealth v. Dias, 
    451 Mass. 463
    , 468 (2008).   In doing so, we consider "the crime charged,
    the possible defenses, the possible significance of the
    [privileged] testimony, and other relevant factors."    
    Id. at 468-469,
    quoting 
    Roviaro, 353 U.S. at 62
    .
    We agree with the second motion judge that the Commonwealth
    properly invoked the informant privilege.   As the Commonwealth
    noted, the individuals identified in the Orlando reports have a
    history of violent crimes, including against witnesses in this
    case.18   The threat of violence against witnesses posed by these
    individuals has been so great that a single justice of this
    court ordered the deposition of Porreca before trial, out of
    concern that he would be killed before testifying.     Porreca
    remained in hiding for at least eighteen months before the
    defendants' trial, in part out of fear of retribution by
    Angelesco and Giangrande.
    We also agree with the second motion judge that the
    defendants failed to challenge adequately the assertion of the
    privilege.   While the confidential informant's identity and the
    18Angelesco pleaded guilty to the 2006 stabbing of a
    witness who, at the hearing on the defendants' first motion for
    a new trial, had accused Angelesco of committing the murder.
    The State police have also received reports that Angelesco and
    Giangrande were seeking retribution against another witness who
    implicated them in the killing.
    41
    information that might be gained from the informant was
    certainly relevant to the defendants' theory, the defendants
    failed to establish its materiality.    The confidential informant
    provided no details "beyond a threadbare rumor" to support his
    allegation that Angelesco and Giangrande committed the murder.
    
    Bonnett, 472 Mass. at 849
    .    The confidential informant was also
    not a percipient witness and had not learned the information
    from a percipient witness or the alleged killers.    Contrast 
    id. ("At a
    minimum, the question whether the informant was a
    percipient witness to the shooting, or whether he had spoken to
    a percipient witness, should have been explored").    Rather, the
    confidential informant was merely relaying inadmissible,
    immaterial "word on the street" information about the killing.
    We conclude that the judge properly denied the defendants'
    motion for disclosure of the confidential informant's identity.19
    5.   Review under G. L. c. 278, § 33E.   Having carefully
    reviewed the entire record pursuant to our duty under G. L.
    c. 278, § 33E, we discern no reason to order a new trial or to
    reduce the degree of guilt.
    Judgments affirmed.
    19Because we agree that the defendants failed to establish
    the materiality of the confidential informant's identity, we do
    not reach the balancing test that constitutes the second stage
    of the analysis.