Karen Kallen-Zury v. United States ( 2023 )


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  • USCA11 Case: 20-12385     Document: 70-1       Date Filed: 01/12/2023   Page: 1 of 23
    [DO NOT PUBLISH]
    In the
    United States Court of Appeals
    For the Eleventh Circuit
    ____________________
    No. 20-12385
    ____________________
    KAREN KALLEN-ZURY,
    Petitioner-Appellant,
    versus
    UNITED STATES OF AMERICA,
    Respondent-Appellee.
    ____________________
    Appeal from the United States District Court
    for the Southern District of Florida
    D.C. Docket Nos. 1:17-cv-21269-JEM and 1:12-cr-20757-JEM-1
    ____________________
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    2                      Opinion of the Court                 20-12385
    Before JORDAN, LUCK, and LAGOA, Circuit Judges.
    PER CURIAM:
    After a five-week trial, a jury found Karen Kallen-Zury guilty
    on various counts relating to Medicare fraud. During the trial, the
    jury heard from many witnesses and was presented with many doc-
    uments corroborating the government’s theory of the case and dis-
    crediting Kallen-Zury’s testimony. Following the district court’s
    denial of her 
    28 U.S.C. § 2255
     motion to vacate her conviction,
    Kallen-Zury appeals the denial and argues that her trial counsel
    should have called several witnesses in her defense, that counsel’s
    failure to do so constituted ineffective assistance of counsel, and
    that we should vacate her conviction and grant her a new trial.
    With the benefit of oral argument, and for the reasons ex-
    plained below, we find that trial counsel’s decision not to call these
    witnesses did not prejudice her. Accordingly, we affirm.
    I.     FACTUAL AND PROCEDURAL BACKGROUND
    A.     Underlying Criminal Case
    This is the fourth time Kallen-Zury has come before this
    Court regarding her trial. We outlined the facts of this case in our
    decisions denying Kallen-Zury’s prior appeals. United States v.
    Kallen-Zury (Kallen-Zury I), 629 F. App’x 894 (11th Cir. 2015);
    United States v. Kallen-Zury (Kallen-Zury II), 710 F. App’x 365
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    20-12385                    Opinion of the Court                                  3
    (11th Cir. 2017); see also United States v. Kallen-Zury (Kallen-Zury
    III), 736 F. App’x 848 (11th Cir. 2018). 1
    “Kallen-Zury co-owned and operated Hollywood Pavilion
    (‘HP’)—a mental health facility that included both inpatient and
    outpatient treatment programs”—as well as “a nursing home and
    rehabilitation center named Hollywood Hills (‘HH’) on the same
    premises.” Kallen-Zury I, 629 F. App’x at 897. During her tenure
    at HP, the facility, which received Medicare reimbursements, paid
    recruiters to bring patients to HP. 
    Id.
     This is illegal. 
    Id.
     “The
    backbone of the government’s case was the testimony of several
    patient recruiters”—“Keith Humes, Jean Luc Veraguas, Mathis
    Moore, Curtis Gates, and Gloria Himmons, who worked as a sub-
    recruiter under Humes”—“who pleaded guilty to Medicare fraud
    related to HP and other facilities.” 
    Id.
    “These recruiters would find patients from as far away as
    Maryland and would pay to have the patients ride buses down to
    HP in Hollywood, Florida.” Kallen-Zury II, 710 F. App’x at 367.
    “Most of the[se] patients were drug addicts who did not need the
    psychiatric services offered at HP.” 
    Id.
     Accordingly, “the conspira-
    tors often falsified the patients’ records to reflect serious psychiatric
    problems or told the patients to [say they had] psychiatric issues
    1 Kallen-Zury has acknowledged that “the actual testimony that was presented
    at the initial trial in 2013 has been fairly presented in the prior opinions of this
    Court,” although she disputes the testimony’s truthfulness.
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    4                      Opinion of the Court               20-12385
    upon admission” to HP. 
    Id.
     HP would then pay the recruiter for
    each patient the recruiter sent to its facility. See 
    id.
     at 367–68.
    “Additionally, HP . . . only admit[ted] patients who had
    enough days on their Medicare plans to have their treatment peri-
    ods paid for by the government.” Kallen-Zury I, 629 F. App’x at
    897. When the Medicare money ran out for a patient, the facility
    would stop treatment and dismiss the patient. 
    Id.
     “Through this
    scheme, HP filed tens of millions of dollars in fraudulent claims to
    Medicare.” 
    Id.
     “Some . . . recruiters also ran halfway houses and
    made extra money when HP referred discharged patients to those
    facilities.” 
    Id.
    “At trial, the recruiters explained that HP had them enter
    into contracts that stated they were providing either ‘case manage-
    ment’ or ‘marketing’ services.” Kallen-Zury II, 710 F. App’x at 367–
    68. “HP also asked the recruiters to submit reports documenting
    their purported performance of these services.” 
    Id. at 368
    . “The
    recruiters’ reports, however, were false,” as the recruiters “were
    never asked to and never did provide these other services.” 
    Id.
     “In-
    stead, they were paid solely to refer patients.” 
    Id.
    Several recruiters, each of whom testified under a grant of
    immunity, claimed to have discussed with Kallen-Zury how HP
    would pay them to recruit patients. Some recruiters also claimed
    that they discussed their recruiting efforts with other HP employ-
    ees. And Himmons testified that she discussed recruiting patients
    for HP with Kallen-Zury herself.
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    20-12385                    Opinion of the Court                                 5
    The government also produced various documents at trial,
    including a “patient register” that tracked which patients were re-
    ferred by which recruiters. 2 The government additionally pre-
    sented the testimony of Dr. Gumer to explain that most of the pa-
    tients admitted to HP did not need psychiatric treatment, either
    because they only had substance abuse issues or because they were
    homeless.
    The defendants, including Kallen-Zury, argued “that they
    acted in good faith and believed the recruiters were providing law-
    ful ‘marketing’ services.” Kallen-Zury I, 629 F. App’x at 897. “They
    argued that HP’s lawyers drafted the contracts with the recruiters
    and instructed HP’s management [on] how to ensure that their
    agreements with the recruiters fell within statutory and regulatory
    ‘safe harbor’ provisions.” 
    Id.
     at 897–98.
    2 At trial, an agent testified that the patient register was found on Kallen-Zury’s
    office computer, which Kallen-Zury denied maintaining and having a copy of,
    prompting the government in closing to use this contradiction to attack her
    credibility. “The prosecutor sarcastically called her ‘unlucky’ for having such
    an important document on her computer without even knowing it.” Kallen-
    Zury I, 629 F. App’x at 898. “After [the] trial, the government realized that the
    disc containing the register had been mislabeled by someone from the Depart-
    ment of Health and Human Services.” 
    Id.
     “Although the prosecutors and the
    lead investigator did not know it, agents had found the document on the com-
    puter of another HP employee.” 
    Id.
     This discovery prompted Kallen-Zury to
    move for a new trial, which the district court denied. 
    Id.
     We affirmed, finding
    that there was no harmful error in this testimony, given the weight of evidence
    against her. 
    Id.
     at 899–900, 915. This issue has therefore been resolved and is
    not part of the current appeal.
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    6                      Opinion of the Court                 20-12385
    After the government rested, trial counsel for Kallen-Zury,
    Michael Pasano—who had implied in his opening statement that
    he would call several witnesses—ended up only calling Kallen-
    Zury as a fact witness. 3 Pasano told the jury that they would hear
    testimony discussing admission practices for people with mental
    health issues along with substance abuse issues, and testimony dis-
    cussing the operation of HP. Ultimately, Pasano made the decision
    to put Kallen-Zury on the stand first to try to catch the government
    off guard at the end of its four-week case. The theory was that the
    government was so focused on its own witnesses, that it may have
    been unprepared to cross-examine Kallen-Zury. Pasano hoped to
    get her off the stand in one day without the government impugn-
    ing her credibility too much, as her credibility was the key to Pas-
    ano’s theory of the case: that Kallen-Zury attempted to comply
    with all laws in good faith. Pasano discussed this strategy with
    Kallen-Zury during trial.
    On the stand, Kallen-Zury testified that she thought these
    recruiters constituted legitimate marketing services for the hospi-
    tal, a belief which she claimed HP’s attorneys verified. After
    Kallen-Zury finished testifying, Pasano introduced some docu-
    ments and a summary witness that he believed would not under-
    mine Kallen-Zury’s testimony.
    3 Pasano
    also called two character witnesses and one summary witness who
    summarized HP’s financial transactions.
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    20-12385               Opinion of the Court                         7
    At a later 
    28 U.S.C. § 2255
     hearing, Pasano stated that he
    made the “tactical choice” not to call the witnesses at issue in this
    appeal after Kallen-Zury testified in her own defense. Pasano did
    so because he did not think the remaining witnesses would signifi-
    cantly move the needle in the jury’s minds, and because calling
    those witnesses would provide an opportunity for the government
    to undermine Kallen-Zury’s testimony. As the trial progressed and
    the district court ruled on various issues, Kallen-Zury focused on
    asserting a “good faith” defense, a strategy which Pasano and
    Kallen-Zury discussed. In light of this defense, the credibility of
    Kallen-Zury was paramount. Kallen-Zury I, 629 F. App’x at 898.
    Because the credibility of Kallen-Zury was, in Pasano’s mind, criti-
    cal to victory at trial, he determined to focus on this good-faith de-
    fense and not put other fact witnesses on the stand that could un-
    dermine her credibility or muddy the waters.
    This strategy ultimately failed. The jury found Kallen-Zury
    and others guilty of all the charges against them, which for Kallen-
    Zury included: (1) conspiracy to commit health care fraud and wire
    fraud, 
    18 U.S.C. § 1349
    ; (2) wire fraud, 
    18 U.S.C. § 1343
    ; (3) health
    care fraud, 
    18 U.S.C. § 1347
    ; (4) conspiracy to defraud the United
    States and to pay and receive kickbacks in connection with a federal
    health-care benefit program, 
    18 U.S.C. § 371
    ; and (5) payment of
    kickbacks in connection with a federal health-care benefit program,
    42 U.S.C. § 1320a–7b(b)(2)(A). Kallen-Zury I, 629 F. App’x at 898.
    The judge sentenced Kallen-Zury to twenty-five years in prison.
    B.     Previous Appeals
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    8                        Opinion of the Court                   20-12385
    Kallen-Zury has come before this Court three times before
    this present appeal regarding her trial. After her conviction, Kallen-
    Zury filed a direct appeal. We affirmed her conviction and the dis-
    trict court’s denial of her motion for a new trial. See Kallen-Zury
    I, 629 F. App’x at 897, 899–900. We denied her motion for recon-
    sideration and for en banc review. Then, in 2016 and 2017, Kallen-
    Zury filed motions under Federal Rule of Criminal Procedure
    33(b)(1) for a new trial based on newly discovered evidence. The
    district court denied both motions, and we affirmed those decisions
    on appeal. Kallen-Zury II, 710 F. App’x at 371–73; Kallen-Zury III,
    736 F. App’x at 852 . We concluded that the new evidence Kallen-
    Zury highlighted did not warrant a new trial because it was largely
    cumulative or impeaching, and because it did not undermine con-
    fidence in the integrity of the verdict. See Kallen-Zury II, 710 F.
    App’x at 372–73; Kallen-Zury III, 736 F. App’x at 851.
    C.     Motion to Vacate
    When those attempts failed, Kallen-Zury filed the § 2255
    motion to vacate at issue in this appeal, in which she detailed the
    prejudice she suffered at trial as a result of her trial counsel not call-
    ing various witnesses or presenting certain documents. In her
    § 2255 motion to vacate, Kallen-Zury argued that she should have
    a new trial because Pasano did not call Vala Wagie, Rocky Da-
    vidson, Angela Rosier, Aaron Danzig, Melvin Hunter, and Dr. Jef-
    frey Danziger as witnesses, and did not present various documents,
    including invoices from the law firm Baker Hostetler, which ad-
    vised HP and Kallen-Zury during this time. Kallen-Zury described
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    20-12385               Opinion of the Court                        9
    in her motion the testimony each of these witnesses—who testified
    at the evidentiary hearing on the § 2255 motion—would have pro-
    vided had Pasano called them to the stand. We set forth the de-
    scriptions of testimony as follows.
    Vala Wagie, a risk management professional, would have
    provided character testimony, and her opinion that HP was run
    well. She would also testify that Kallen-Zury never asked her to
    hide or alter any documents, that Kallen-Zury was not in charge of
    clinical decisions at HP, and that all patients needed the treatment
    they received.
    Rocky Davidson, a certified public accountant who did out-
    sourced accounting for HP, would have testified that HP was not
    profitable enough to pay Kallen-Zury tens of millions of dollars and
    that a large portion of her income came from an unrelated nursing
    home not subject to this investigation.
    Angela Rosier would have testified that she oversaw patient
    charts and records, that she was unaware of any falsifications or
    alterations of those charts, that she was unaware of any mistreat-
    ment or unnecessary treatment of patients, and that Kallen-Zury
    had nothing to do with patient care or treatment. Rosier was also
    involved in gathering records to comply with the subpoena and
    would testify that she was unaware of any effort to obstruct justice.
    Aaron Danzig, an attorney, would have testified about his
    work complying with the government’s document requests to HP.
    He instructed Kallen-Zury on how to respond to those requests,
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    10                      Opinion of the Court                 20-12385
    sent her newspaper articles and indictments as to other fraud inves-
    tigations as part of that advice, which the government later claimed
    was evidence of fraudulent intent, and he was working on having
    the original patient register scanned and sent to the government
    when the register was seized pursuant to a search warrant.
    Melvin Hunter, who oversaw the Admissions Department
    at HP and was tried separately, would have testified that patients
    who arrived at the facility were usually “pre-cleared” through an
    interview process—explaining the high admission rate the govern-
    ment claimed proved fraud—but that doctors at HP ultimately
    made the final admission decision. Hunter also would have testi-
    fied that he never told Himmons to lie nor told Himmons that
    Kallen-Zury was not satisfied with the number of patients Him-
    mons was referring to HP. Additionally, Hunter would have stated
    that Kallen-Zury did not have a role in altering the patient register,
    as it was his job, that he altered the columns in the patient register,
    and that the government seized those hard copy binders of patient
    registers during their search of the premises. Hunter also claimed
    he would have waived his Fifth Amendment rights if he testified at
    Kallen-Zury’s trial.
    Dr. Jeffrey Danziger, the defense’s medical expert, would
    have testified that each of the nineteen patients he reviewed were
    properly admitted, and that the patient charts were internally con-
    sistent, meaning doctoring them would have required dozens of
    people to be in on the fraud. He would also have explained the
    relationship between substance abuse and mental health issues,
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    20-12385               Opinion of the Court                      11
    which was important because many patients at HP suffered from
    both and because the government cited to patients with substance
    abuse as proof of HP admitting patients that did not suffer from
    mental health issues.
    The district court referred Kallen-Zury’s motion to vacate to
    a magistrate judge. After three days of evidentiary hearings and a
    thorough review of the record, the magistrate judge recommended
    the motion to vacate be denied. The magistrate judge addressed
    each potential witness, summarized their testimony at the eviden-
    tiary hearings, and then made the following credibility and bias as-
    sessments.
    The magistrate judge found that Wagie was credible within
    the areas where she had knowledge during her employment at HP.
    But Wagie admitted she had no knowledge regarding HP’s mar-
    keting or recruiting operations. Additionally, the magistrate judge
    noted that Wagie had a “bias trend . . . in favor of Kallen-Zury.”
    The magistrate judge found Davidson’s testimony to be
    knowledgeable and credible. But given that he admitted all the
    payments shown on the government’s trial chart came from HP’s
    account, and not the nursing home’s account, his trial testimony
    that Kallen-Zury’s money came from sources other than HP would
    have had minimal value.
    Rosier was evasive and not credible, according to the magis-
    trate judge, particularly where she discussed signed blank treat-
    ment plan sheets in patient charts. After acknowledging that it was
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    12                     Opinion of the Court                20-12385
    wrong to have signed blank patient sheets, she provided excuses
    and conflicting explanations about why examples of those signed
    blank sheets existed at HP, when confronted with multiple such
    instances during cross-examination.
    Danzig was generally credible but tainted by self-interest in
    justifying his handling of the government subpoenas, according to
    the magistrate judge. Therefore, the magistrate judge found that
    his testimony would have little value.
    Hunter was biased and inconsistent. According to the mag-
    istrate judge, he wanted to retaliate against the government given
    his prosecution in a parallel case. The magistrate judge also found
    Hunter’s assertion that he would have waived his Fifth Amend-
    ment rights and testified at Kallen-Zury’s trial was contradicted by
    the fact that he invoked those same rights when he was subpoe-
    naed by the grand jury in Kallen-Zury’s case. Additionally, when
    Kallen-Zury’s trial counsel asked Hunter to testify, his attorney
    stated Hunter would assert his Fifth Amendment rights if called to
    the stand.
    Dr. Danziger was credible, but his testimony was of limited
    value according to the judge. His review was only based on a few
    patients (nineteen out of thousands), and his opinions were predi-
    cated on the assumption that all the chart entries were true and
    accurate, even though he had no corroboration to support that as-
    sumption.
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    20-12385                Opinion of the Court                         13
    The magistrate judge also considered Pasano’s explanation
    for his actions and found him to be credible and reliable. She con-
    cluded Pasano provided reasonable explanations as to why he
    made the decisions he did at trial, based on the dynamics of the trial
    and the factors present at that time.
    After reviewing the witnesses’ testimony from the eviden-
    tiary hearing and making credibility determinations, the magistrate
    judge found that Kallen-Zury had not satisfied either prong of the
    test for ineffective assistance of counsel under Strickland v. Wash-
    ington, 
    466 U.S. 668
    , 687 (1984). As to the first prong, i.e., deficient
    performance, none of Pasano’s decisions on the presentation of
    witnesses and documents were of the kind that no competent
    counsel would have taken. This was especially true given the
    strong presumption that his actions fell within the wide range of
    reasonable conduct given his “ample prior trial experience.” Mov-
    ing to the second prong—prejudice—the magistrate judge found
    that there was no reasonable probability that Kallen-Zury’s trial
    would have had a different outcome had Pasano introduced those
    witnesses or documents, and therefore Kallen-Zury could not
    show prejudice. The magistrate judge reviewed his or her credibil-
    ity determinations to conclude that the witnesses were either cred-
    ible, but without valuable testimony, or not credible and incon-
    sistent. Because Kallen-Zury could not satisfy either prong of
    Strickland, the magistrate judge recommended denying the mo-
    tion to vacate.
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    14                      Opinion of the Court                  20-12385
    On April 30, 2020, the district court, after reviewing the rec-
    ord, adopted the magistrate judge’s report and recommendation.
    The district court then issued a certificate of appealability “as to
    [Kallen-Zury’s] claim that her former trial counsel was ineffective
    for failing to call any witnesses at trial other than [Kallen-Zury] her-
    self.”
    Now, in her fourth appeal to this Court regarding her trial,
    Kallen-Zury contends that the district court erred in denying her
    motion to vacate under § 2255.
    II.    STANDARD OF REVIEW
    In a § 2255 proceeding, we review the district court’s legal
    conclusions de novo and the underlying factual findings for clear
    error. Lynn v. United States, 
    365 F.3d 1225
    , 1232 (11th Cir. 2004)
    (citation omitted). “We allot ‘substantial deference to the fact-
    finder . . . in reaching credibility determinations with respect to
    witness testimony.’” Devine v. United States, 
    520 F.3d 1286
    , 1287
    (11th Cir. 2008) (quoting United States v. McPhee, 
    336 F.3d 1269
    ,
    1275 (11th Cir. 2003)).
    III.     ANALYSIS
    A.          Scope of Appeal
    Before getting to the merits of the case, there are two related
    procedural issues we must address. On appeal, Kallen-Zury argues
    that Pasano was ineffective for three reasons: (1) for failing to in-
    troduce various documents, (2) for artificially limiting Dr. Dan-
    ziger’s potential testimony due to counsel’s Federal Rule of
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    20-12385                   Opinion of the Court                              15
    Criminal Procedure 16 violation 4 and decision to limit the sample
    size of Dr. Danziger’s review to nineteen patients, and (3) for fail-
    ing to get Kallen-Zury’s informed consent before deciding not to
    call various witnesses at trial. Unfortunately for Kallen-Zury, the
    first two issues are outside the certificate of appealability, and the
    third issue has been waived because she failed to raise it before the
    district court.
    “[I]n an appeal brought by an unsuccessful habeas peti-
    tioner, appellate review is limited to the issues specified in the [cer-
    tificate of appealability].” Turner v. Sec’y, Dep’t of Corr., 
    991 F.3d 1208
    , 1211 n.1 (11th Cir. 2021) (quoting Murray v. United States,
    
    145 F.3d 1249
    , 1250–51 (11th Cir. 1998)). The certificate of appeal-
    ability allowed Kallen-Zury to appeal her claim “that her former
    trial counsel was ineffective for failing to call any witnesses at trial
    other than [Kallen-Zury] herself.” The district court expressly lim-
    ited the scope of the certificate of appealability to the issue of wit-
    nesses, not documents. Therefore, we will not consider Kallen-
    Zury’s arguments about Pasano’s failure to introduce various doc-
    uments at the trial or his decisions affecting the scope of Dr. Dan-
    ziger’s testimony.
    4 At trial, the government made a Rule 16 objection to the use of the charts
    that Dr. Danziger had reviewed, arguing that Pasano failed to disclose them.
    This objection came after Kallen-Zury rested her case and after Pasano de-
    cided not to call Dr. Danziger. The district court ultimately excluded a portion
    of Dr. Danziger’s testimony if Kallen-Zury’s co-defendant called him to testify.
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    16                         Opinion of the Court                20-12385
    Though the argument was not included in the § 2255 mo-
    tion, on appeal, Kallen-Zury argues that once she and counsel
    agreed they would present exculpatory witnesses, counsel needed
    her informed consent not to call them. She claims that counsel’s
    performance was deficient for failing to get such consent. This ar-
    gument might require us to decide as a matter of first impression
    whether the decision to call witnesses at trial belongs to the lawyer
    or the client. But “we have repeatedly held that ‘an issue not raised
    in the district court and raised for the first time in an appeal will not
    be considered by this court.’” Walker v. Jones, 
    10 F.3d 1569
    , 1572
    (11th Cir. 1994) (citation omitted). For this reason, we will not con-
    sider Kallen-Zury’s arguments about Pasano’s failure to get her in-
    formed consent not to call any fact witnesses other than Kallen-
    Zury herself.
    With these procedural issues resolved, we turn to the merits
    of Kallen-Zury’s ineffective assistance claim.
    B.       Strickland Analysis
    To prevail on an ineffective assistance of counsel claim, a pe-
    titioner must “demonstrate both that (1) ‘counsel’s performance
    was deficient,’ and (2) ‘the deficient performance prejudiced the de-
    fense.’” United States v. Webb, 
    655 F.3d 1238
    , 1258 (11th Cir. 2011)
    (quoting Strickland, 
    466 U.S. at 687
    ). “We may consider the prongs
    of the Strickland test in either order, and the defendant must show
    that both prongs are satisfied in order to demonstrate a Sixth
    Amendment violation.” 
    Id.
     (citation omitted). This standard is
    necessarily a fact-intensive one, requiring a court to “consider[] all
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    20-12385               Opinion of the Court                        17
    the circumstances” when evaluating counsel’s performance.
    Strickland, 
    466 U.S. at 688
    . If a defendant makes an insufficient
    showing on one of the requisite prongs, we need not address the
    other prong. 
    Id. at 697
    ; Dingle v. Sec’y for Dep’t of Corr., 
    480 F.3d 1092
    , 1100 (11th Cir. 2007) (citation omitted).
    To establish prejudice under the second prong of Strickland,
    a defendant must show “a reasonable probability that, but for coun-
    sel’s unprofessional errors, the result of the proceeding would have
    been different.” Strickland, 
    466 U.S. at 694
    . “A reasonable proba-
    bility is a probability sufficient to undermine confidence in the out-
    come.” 
    Id.
     In other words, “[i]t is not enough for the defendant to
    show that the errors had some conceivable effect on the outcome
    of the proceeding.” 
    Id. at 693
    . The petitioner must show instead
    that counsel’s deficient representation rendered the result of the
    trial unfair. See 
    id. at 697
    . The prejudice component of the Strick-
    land standard thus reflects “[t]he purpose of the Sixth Amendment
    guarantee of counsel,” which is to “ensure that a defendant has the
    assistance necessary to justify reliance on the outcome of the pro-
    ceeding.” 
    Id.
     at 691–92. This Court has recognized that, given the
    principles and presumptions associated with ineffective assistance
    claims, “the cases in which habeas petitioners can properly prevail
    are few and far between.” Chandler v. United States, 
    218 F.3d 1305
    ,
    1313 (11th Cir. 2000) (ellipsis omitted) (quoting Waters v. Thomas,
    
    46 F.3d 1506
    , 1511 (11th Cir. 1995) (en banc)).
    Strickland prejudice presents a mixed question of law and
    fact, making our review plenary. See, e.g., Brooks v. Comm’r, Ala.
    USCA11 Case: 20-12385       Document: 70-1        Date Filed: 01/12/2023        Page: 18 of 23
    18                        Opinion of the Court                    20-12385
    Dep’t of Corr., 
    719 F.3d 1292
    , 1300 (11th Cir. 2013). Underlying
    factual determinations, however, are subject to clear error review.
    See Devine, 
    520 F.3d at 1287
    .
    Here, we conclude that the district court did not err in de-
    termining Kallen-Zury did not suffer prejudice. The district court
    found that her proposed witnesses were either credible but could
    not offer valuable testimony, or were not credible, and so their tes-
    timony would not have changed the outcome of the trial. We also
    conclude that the magistrate judge’s thorough factual findings set
    forth in the report and recommendation, which were adopted by
    the district court, are not clearly erroneous, especially given the
    substantial deference we afford to the factfinder as to credibility de-
    terminations. See Devine, 
    520 F.3d at 1287
    . We briefly discuss
    each proposed witness in turn. 5
    Wagie, although credible according to the magistrate judge,
    was not at HP during the key period in this case, had no knowledge
    of HP’s accounting or marketing operations, and exhibited bias in
    favor Kallen-Zury. The combination of her lack of first-hand
    knowledge and exhibited bias led the magistrate judge to discount
    her potential testimony. Given her lack of firsthand knowledge on
    the critical issues of the case and her bias, it was not error to find
    5
    Because we conclude that Kallen-Zury did not establish prejudice under
    Strickland, we need not determine whether the district court correctly deter-
    mined that her counsel did not exhibit deficient performance. See Strickland,
    
    466 U.S. at 697
    .
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    20-12385               Opinion of the Court                      19
    that Wagie’s testimony would not have resulted in a different out-
    come at trial.
    Davidson, while credible in the eyes of the magistrate judge,
    would not have provided valuable testimony, as the financial chart
    he would testify about was introduced by Pasano to avoid the risks
    of cross-examination. The only other testimony Davidson had to
    offer was his statement that the money Kallen-Zury received came
    from sources other than HP. But Davidson admitted at the eviden-
    tiary hearing that all the payments made to Kallen-Zury came from
    HP’s bank account, not the nursing home’s account or any other
    account. Regardless of how money was moving in the back-
    ground, the money paid to Kallen-Zury came from HP. Thus, it
    was not error to conclude that this testimony would not have
    changed the outcome of the trial.
    The magistrate judge determined that Rosier was not credi-
    ble, as she tried to justify the practice of signing blank treatment
    forms after saying such practices were unacceptable. During her
    cross-examination at the evidentiary hearing, she stated that doc-
    tors should not sign blank treatment forms. But when she was pre-
    sented with three separate documented instances of this happening
    at HP, she came up with implausible excuses for each example,
    such as the doctor probably knew the treatment in his head, even
    though she had no knowledge of the specific doctor in that case.
    Her lack of credibility would not have persuaded a reasonable jury.
    Danzig seemed mostly interested in justifying his handling
    of the government subpoena, and so the magistrate judge found
    USCA11 Case: 20-12385      Document: 70-1      Date Filed: 01/12/2023     Page: 20 of 23
    20                      Opinion of the Court                 20-12385
    his testimony was colored by self-interest. Given this, the magis-
    trate concluded that his testimony was not valuable. Even if the
    jury determined Danzig were not testifying out of self-interest, all
    he would have told the jury was that Kallen-Zury used lawyers at
    Danzig’s firm to comply with the government subpoena. But the
    jury knew this information already, as the government presented
    documents showing the law firm’s involvement, Kallen-Zury also
    testified to that fact, and Pasano reiterated this during closing argu-
    ments. Therefore, Danzig’s testimony would have been cumula-
    tive and would not contradict the facts underlying Kallen-Zury’s
    crimes.
    As for Hunter, we already concluded, in Kallen-Zury II, that
    neither his testimony about Kallen-Zury’s role with respect to the
    patient register—nor his testimony contradicting Gloria Him-
    mons’s trial testimony—would’ve impacted the outcome of
    Kallen-Zury’s trial. 710 F. App’x at 370–73. What’s more, the mag-
    istrate judge found his testimony at the evidentiary hearing to be
    inconsistent and lacking in credibility. Hunter’s claim that he
    would have testified at Kallen-Zury’s trial was contradicted by the
    fact he invoked his Fifth Amendment rights before the grand jury.
    Additionally, the magistrate judge believed Hunter “had an obvi-
    ous axe to grind against the government after having been prose-
    cuted and acquitted in a parallel case,” further reducing his credi-
    bility. Hunter was uncooperative and contradictory in his cross-
    examination during the evidentiary hearing. For instance, he de-
    nied that Himmons, a recruiter for HP, actually sent patients to
    USCA11 Case: 20-12385     Document: 70-1      Date Filed: 01/12/2023     Page: 21 of 23
    20-12385               Opinion of the Court                        21
    HP, but admitted she was a referral source. Then, after admitting
    he did not work with Dr. Gumer—a former HP doctor and gov-
    ernment witness—or know what Dr. Gumer did with patients,
    Hunter said that Dr. Gumer was lying when he admitted to falsify-
    ing patient records at trial. When shown multiple duplicate in-
    voices submitted to or by HP, Hunter claimed the records did not
    seem odd to him. Hunter was also unconcerned over a letter he
    was shown from a doctor at HP that outlined three practices the
    doctor thought were illegal, because according to Hunter, that was
    just what the doctor believed. Hunter admitted on cross-examina-
    tion that HP tracked referrals “indirectly” but claimed this tracking
    was “not really” important. He later contradicted himself by ad-
    mitting that the tracking was important to HP. We thus conclude
    that the district court’s ruling as to this witness was not erroneous.
    As to Dr. Danzinger, his testimony, although found to be
    credible, was of little value according to the magistrate judge, given
    that he analyzed only nineteen of the thousands of patients at HP
    during the period in question. Additionally, his analysis assumed
    the veracity of the treatment forms, even though he had no cor-
    roboration for such an assumption. Given this limited sample size,
    and the fact that the key issue in the case came down to Kallen-
    Zury’s credibility with the jury, there is no reasonable probability
    that Dr. Danziger’s testimony would have led to a different out-
    come.
    The testimony from these witnesses—taken together or sep-
    arately—would not have created a reasonable probability that
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    22                     Opinion of the Court                 20-12385
    Kallen-Zury’s trial would have resulted in a different outcome—
    especially given the deferential standard we afford to credibility de-
    terminations of witnesses by the factfinder, in this case the magis-
    trate judge. See McPhee, 
    336 F.3d at 1275
     (“[W]e allot substantial
    deference to the factfinder . . . in reaching credibility determina-
    tions with respect to witness testimony.” (quoting EEOC v. Joe’s
    Stone Crab, Inc., 
    220 F.3d 1263
    , 1285–86 (11th Cir. 2000))). The
    magistrate judge conducted three full days of evidentiary hearings,
    listening to the testimony that each proposed witness would have
    given at Kallen-Zury’s trial. The magistrate judge made certain
    credibility determinations that were reasonable based on our re-
    view of the transcripts, and we will not second guess those deter-
    minations here. Based on those determinations, the magistrate
    judge found that the proposed witnesses would not have changed
    the outcome of the trial. The district court adopted those findings
    and conclusions, and we cannot conclude that this was error.
    Kallen-Zury’s proposed witnesses would have been of lim-
    ited value to her defense, especially considering the weight of evi-
    dence against her presented during the five-week trial. At a trial
    where the key issue became her credibility, Kallen-Zury’s testi-
    mony contradicted the testimony of several government witnesses
    on a number of points. There were several discrepancies between
    Kallen-Zury’s testimony and the testimony of other witnesses (in-
    cluding three patient recruiters and two of Kallen-Zury’s own em-
    ployees), which were sufficient to damage her credibility in the ju-
    rors’ eyes. And so, she cannot show that she was prejudiced by
    USCA11 Case: 20-12385     Document: 70-1      Date Filed: 01/12/2023     Page: 23 of 23
    20-12385               Opinion of the Court                        23
    Pasano’s failure to call these witnesses at trial and therefore cannot
    satisfy the second Strickland prong. See Strickland, 
    466 U.S. at 694
    .
    Thus, her ineffective assistance of counsel claim must fail.
    IV.    CONCLUSION
    For all these reasons, we conclude that the district court did
    not err in concluding that the testimony of the proposed witnesses
    would not have changed the outcome of the trial. As a result,
    Kallen-Zury was not prejudiced by her counsel’s decision not to
    call those witnesses at trial. We therefore affirm the denial of her
    § 2255 motion.
    AFFIRMED.