Full opinion text
Opinion for the Court filed PER CURIAM. PER CURIAM: A group known as the M Street Crew operated a massive drug ring in Northeast Washington, D.C. The Crew sold PCP, as well as ecstasy and some crack cocaine. From late 2002 through March 2004, the government conducted an extensive investigation of the M Street Crew’s activities. As a result of the investigation, 19 defendants were charged with a variety of federal crimes. In this appeal, five of those defendants challenge their convictions and sentences. They raise numerous claims, some common to all defendants and others specific to one or more defendants. Except for one issue related to defendant Blackson’s judgment as to which the government concedes error, we affirm the district court’s judgments in their entirety. I A We describe the facts in the light most favorable to the government, as we must in reviewing a jury verdict of guilt. United States v. Clayborne, 509 F.2d 473, 475 (D.C.Cir.1974); United States v. Alexander, 331 F.3d 116, 127 (D.C.Cir.2003). The five appellants in this case are John Franklin, William Robinson, George Wilson, Joseph Blackson, and William Simmons. In 2002, the FBI and the Metropolitan Police Department of Washington, D.C., initiated an intensive investigation of criminal activity in a four-block area around 18th Street and M Street in Northeast Washington. Officers viewed the neighborhood at the time as “an open air drug-market.” Mar. 28, 2006 AM Trial Tr. at 95 (Officer Carlton Herndon). The air smelled of PCP, and the area was filled with broken vials. Id. at 100; id. at 40 (Officer Michael Morawski). Detectives patrolling the area could easily find bottles of PCP hidden along the edges of buildings and walkways. Id. at 100 (Officer Carlton Herndon). During its investigation, the government uncovered a large-scale drug ring. John Franklin had a supplier outside the M Street Crew from whom he bought at least 15 to 20 gallons of PCP between 2002 and 2004. Mar. 14, 2006 AM Trial Tr. at 65 (Herbert Martin). Franklin, in turn, supplied the M Street Crew primarily with liquid PCP and ecstasy pills. Mar. 22, 2006 AM Trial Tr. at 73-74 (Elizabeth Lee); Apr. 19, 2006 PM Trial Tr. at 29-30 (Roberta Moore). Franklin’s routine was generally consistent. He would obtain PCP from his supplier. Then, Franklin’s common-law wife, Elizabeth Lee, would rebottle the drug into ounce and half-ounce bottles for Franklin to sell on the street or to lower-level dealers. Mar. 22, 2006 PM Trial Tr. at 7 (Elizabeth Lee). Before selling his now-bottled product, Franklin employed a neighborhood woman, Monica Bell, to “test it out.” Id. at 40, 43. Bell sampled Franklin’s PCP about “three times a week” in exchange for occasional “free dippers,” cigarettes soaked in PCP. Apr. 18, 2006 PM Trial Tr. at 82, 86 (Monica Bell). After testing, Franklin would supply the drugs to the Crew. Often, these drug transactions would occur in person. See, e.g., Apr. 27, 2006 AM Trial Tr. at 85 (Omari Minnis) (“Normally I might go to him once, twice a week. Get about a ounce, two ounces.”). When Franklin was not available, however, he delegated to his lieutenants. See, e.g., Apr. 24, 2006 PM Trial Tr. at 32, 38 (Ronnie Tucker); Aug. 11, 2003 Wiretap Tr. at 2-3; May 2, 2006 AM Trial Tr. at 15 (Michael Abney). Franklin sold PCP to those he supplied in half-ounce bottles for $250 and ecstasy pills in ten-packs for $100. Mar. 22, 2006 AM Trial Tr. at 73-74 (Elizabeth Lee); Apr. 20, 2006 PM Trial Tr. at 28-29 (April Jackson). Franklin’s role was not limited to that of a supplier. At trial, other members of the Crew described Franklin as their “organizer” and “leader.” Apr. 24, 2006 AM Trial Tr. at 107 (Ronnie Tucker); May 2, 2006 AM Trial Tr. at 10-12 (Michael Abney). Indeed, members of the Crew brought Franklin in to mediate disputes and to “keep[ ] M Street in order.” May 2, 2006 AM Trial Tr. at 12 (Michael Abney). Even when uninvited, Franklin often played a mediating role between Crew members. See id. at 39. When absent from 18th and M, Franklin would check in on the Crew, sometimes giving advice about their selling methods. See, e.g., Sept. 30, 2003 Wiretap Tr. at 2. Below Franklin in the Crew’s hierarchy were his three lieutenants: William Robinson, George Wilson, and Joseph Blackson. May 2, 2006 AM Trial Tr. at 13-15 (Michael Abney). Those men supplied the Crew with PCP in Franklin’s absence. Id. at 29; Apr. 24, 2006 PM Trial Tr. at 14-15 (Ronnie Tucker). The lieutenants would “take on the situations when John [was] not around as far as money, or drugs or problems that’s going on that’s involved in the area, keep things intact” so as not to mess up the Crew’s “money spot.” May 2, 2006 AM Trial Tr. at 15 (Michael Abney). Them job was “to oversee everything for the top man. To make sure everything on the block going the way that he ... would want it to be and see to it that its foot soldiers everybody taken care of, everybody straight.” May 3, 2006 AM Trial Tr. at 22 (Michael Abney). William “Dee” Robinson was one of Franklin’s closest Mends. Mar. 23, 2006 AM Trial Tr. at 22 (Elizabeth Lee). Robinson “would hold bottles” of PCP for Franklin when he was away from 18th and M, Apr. 27, 2006 AM Trial Tr. at 91 (Omari Minnis), and communicated regularly with Franklin about the Crew’s drug sales and supply, see, e.g., Apr. 24, 2006 PM Trial Tr. at 66-67 (Ronnie Tucker); Aug. 21, 2003 Wiretap Tr. at 1. On Sundays, which Franklin spent with his family, Robinson was sometimes in charge of the Crew. See May 2, 2006 AM Trial Tr. at 28-29 (Michael Abney). George “Shug” Wilson was like a sibling to Franklin. Id. at 35. When Franklin was unavailable, he regularly referred buyers to Wilson, who sold some of the PCP supplied by Franklin. Id. at 29; Apr. 24, 2006 PM Trial Tr. at 15 (Ronnie Tucker). Wilson played an enforcement role in the Crew; he defended its preeminence in the 18th and M area from outsiders, sometimes by force. See Sept. 27, 2003 Wiretap Tr. at 1-2; Oct. 3, 2003 Wiretap Tr. at 1, 4-6; May 3, 2006 PM Trial Tr. at 34-35 (Robin Tamika Hazel) (“Shug pulled his gun out on him and made him leave.... Told him to leave from off his block. This is his block.”). Moreover, like Robinson, Wilson was sometimes in charge of the Crew in Franklin’s absence. May 2, 2006 AM Trial Tr. at 28-29 (Michael Abney). This authority position was apparent to onlookers; a police officer who regularly patrolled 18th and M initially took Wilson to be “in charge” of the Crew. Mar. 28, 2006 PM Trial Tr. at 11, 13-14 (Officer Carlton Herndon). Joseph “Joe Black” Blackson, Franklin’s younger brother, also distributed PCP in Franklin’s absence. In addition, Blackson held drugs for his brother. Apr. 24, 2006 PM Trial Tr. at 17-18 (Ronnie Tucker). In his dealings with an undercover officer, Blackson equated himself with Franklin, stating that “dealing with John is just as dealing with him.” Apr. 4, 2006 PM Trial Tr. at 97 (Officer Donna Leftridge). Blackson was the only one of the lieutenants to be absent from the 18th and M Street area for any length of time during the investigation; he was arrested on July 29, 2003, when police found drugs in the glove compartment of his car. Apr. 12, 2006 PM Trial Tr. at 60-74 (Officer Max Luis Salazar). Blackson was then incarcerated for an indeterminate period of time before returning to 18th and M. See Reply Br. at 69; Aug. 31, 2006 Sent. Hg. at 67. Beneath Franklin’s three lieutenants was a class of “foot soldiers” who made individual sales in the 18th and M area. May 2, 20.06 AM Trial Tr. at 18-19 (Michael Abney). Although the foot soldiers were numerous, only one foot soldier was tried with Franklin and is party to this appeal. William “Mike” Simmons was Franklin’s “loyalest foot soldier.” Id. at 42. Witnesses variously testified that Simmons was Franklin’s “[s]idekick,” “runner,” “helper,” “little man,” and “flunky.” Apr. 19, 2006 PM Trial Tr. at 44 (Roberta Moore); Apr. 27, 2006 AM Trial Tr. at 88 (Omari Minnis). According to one witness, Simmons would do “[wjhatever [Franklin] told him. Sell bottles to people. If [Franklin] ... needed anything done, he’d do it.” May 2, 2006 AM Trial Tr. at 43 (Michael Abney). One of Simmons’ most frequent tasks was to deliver drugs to Franklin or from Franklin to his customers. See, e.g., id. at 51-52; Apr. 19, 2006 PM Trial Tr. at 44 (Roberta Moore); Apr. 24, 2006 PM Trial Tr. at 17 (Ronnie Tucker). B The M Street Crew displayed cohesion both as a business and as a social unit. As a business, the Crew guarded its territory, permitting only Crew members to sell within the 18th and M area. Apr. 27, 2006 AM Trial Tr. at 81-82 (Omari Minnis); Apr. 24, 2006 PM Trial Tr. at 22 (Ronnie Tucker) (‘We ain’t allow nobody to sell drugs around there that wasn’t from around there.”). The Crew used graffiti to mark its territory. See, e.g., Record Materials for Appellee at 95-105. Moreover, the Crew’s monopoly on drug sales within its turf was strictly enforced; if someone from outside the Crew attempted to sell drugs in the Crew’s territory, he would “either get hurt real bad or he wouldn’t make it home.” Apr. 27, 2006 AM Trial Tr. at 82 (Omari Minnis). Economic order was maintained within the Crew as well. Franklin and the lieutenants imposed a rotational system of drug sales whereby the Crew members would “take turns” selling so that “everybody get[s] a fair share.” Apr. 24, 2006 PM Trial Tr. at 5 (Ronnie Tucker). Under this system, each Crew member would be permitted to make a single sale — regardless of the magnitude of the sale — before relinquishing the turf to another Crew member. Apr. 27, 2006 AM Trial Tr. at 80 (Omari Minnis) (“say it was five of us outside, you know, whoever was outside first goes first, come up second, go second. Don’t matter how much they wanted or, you know, they wanted eight dippers it’s your turn.”). The Crew members also protected their turf and each other from potential threats in the form of police officers and outsiders. When police were in the area, Crew members would alert one another to the potential threat. Mar. 28, 2006 AM Trial Tr. at 41 (Officer Carlton Herndon) (‘When I came into the area, either on a bike or a car, they would always give a heads up that I was in the area.”); Apr. 24, 2006 PM Trial Tr. at 7 (Ronnie Tucker) (“We warn each other.”). Similarly, when outsiders attacked Crew members, the Crew fought back, sometimes exchanging gunfire. See, e.g., Apr. 27, 2006 PM Trial Tr. at 6-8 (Omari Minnis); May 2, 2006 AM Trial Tr. at 73-80 (Michael Abney). Finally, the Crew was a cohesive social unit. Crew members socialized together, frequenting local dance clubs. Apr. 6, 2006 AM Trial Tr. at 18-20 (Ricardo Love). Crew members would flash an M-shaped hand signal to one another, signaling their membership in the M Street Crew. See Record Materials for Appellee at 122-23, 125. Musicians at the local clubs recognized the group as a defined unit, giving a “shout out” that the M Street Crew was “[i]n the house.” Apr. 6, 2006 AM Trial Tr. at 20-21 (Ricardo Love). C The massive investigation of the M Street Crew culminated in 39 arrests on March 16, 2004. Mar. 10, 2006 AM Trial Tr. at 45 (Agent Joseph Sopata). Among those arrested and later indicted were Franklin, Robinson, Wilson, Blackson, and Simmons, appellants here. Those five were tried together. After a lengthy trial, the jury convicted each defendant of the bulk of the drug charges leveled against him. The defendants were acquitted of various weapons and violent crime charges. The jury convicted Franklin of one count of conspiracy to distribute and possess with intent to distribute a controlled substance (Count 1, Judgment of Franklin at 1; Verdict at 1-3); one count of RICO conspiracy (Count 2, Judgment of Franklin at 2; Verdict at 12-13); one count of continuing criminal enterprise (Count 3, Judgment of Franklin at 2; Verdict at 4-11); 16 counts of distribution of and possession with the intent to distribute PCP, half of which occurred within 1,000 feet of a school (Counts 8, 10, 17, 21, 30, 36-37, 41-42, 44, 51, 53, 58, 63, 69, and 77, Judgment of Franklin at 2-3; Verdict at 16-20); three counts of distribution of cocaine base, one of which occurred within 1,000 feet of a school (Counts 45, 52, and 67, Judgment of Franklin at 2; Verdict at 17-18); five counts of distribution of ecstasy and possession with the intent to distribute ecstasy, two of which occurred within 1,000 feet of a school (Counts 50, 57, 68, and 77-78, Judgment of Franklin at 2-3; Verdict at 17-20); 27 counts of unlawful use of a communication facility (Counts 83-109, Judgment of Franklin at 3; Verdict at 20-23); two counts of use or possession of a firearm during a drug-trafficking offense (Counts 135 and 137, Judgment of Franklin at 3; Verdict at 14-15); and two counts of being a felon in possession of a firearm (Counts 136 and 138, Judgment of Franklin at 3; Verdict at 14-15). Franklin was also acquitted of several of the charges against him, most notably of all murder, assault, and related charges (Counts 2, 129-32, 148-49, and 158-59, Verdict at 12, 14-15). In acquitting Franklin of those charges, the jury found that the RICO conspiracy did not involve murder (Count 2, Verdict at 12). Franklin’s lieutenants were also convicted of both narcotics and RICO conspiracies, as well as of various distribution charges, but acquitted of violent crime charges. Unlike Franklin, none of the lieutenants was charged with leading a continuing criminal enterprise. Blackson was convicted of one count of conspiracy to distribute and possess with intent to distribute a controlled substance (Count 1, Judgment of Blackson at 1; Verdict at 24-26); one count of RICO conspiracy (Count 2, Judgment of Blackson at 2; Verdict at 26-27); eleven counts of distribution of PCP, most occurring within 1,000 feet of a school (Counts 6, 9-10, 13, 16, 19, 23-24, 27, 33, and 42, Judgment of Black-son at 2; Verdict at 27-29); two counts of possession with intent to distribute ecstasy (Counts 7 and 43, Judgment of Blackson at 2; Verdict at 27, 29); one count of using, carrying, or possessing a firearm during a drug trafficking crime (Count 133, Judgment of Blackson at 2; Verdict at 27); and one count of possession of a firearm by a convicted felon (Count 134, Judgment of Blackson at 2; Verdict at 27). The jury found that the RICO conspiracy did not involve murder (Count 2, Verdict at 26). Robinson, similarly, was convicted of one count of conspiracy to distribute and possess with intent to distribute a controlled substance (Count 1, Judgment of Robinson at 1; Verdict at 30-31); one count of RICO conspiracy (Count 2, Judgment of Robinson at 2; Verdict at 32); two counts of PCP distribution, one within 1,000 feet of a school (Counts 36 and 58, Judgment of Robinson at 2; Verdict at 33); one count of possession with the intent to distribute PCP (Count 73, Judgment of Robinson at 2; Verdict at 33); and three counts of unlawful use of a communication facility (Counts 96, 101, and 103, Judgment of Robinson at 2; Verdict at 34). The jury found that the RICO conspiracy did not involve murder (Count 2, Verdict at 32). Wilson, the third lieutenant, was convicted of one count of conspiracy to distribute and possess with an intent to distribute a controlled substance (Count 1, Judgment of Wilson at 1; Verdict at 41-42); one count of RICO conspiracy (Count 2, Judgment of Wilson at 2; Verdict at 43); and three counts of unlawful use of a communication facility (Counts 104-06, Judgment of Wilson at 2; Verdict at 44). The jury found that the RICO conspiracy did not involve murder (Count 2, Verdict at 43). Finally, Simmons, the only foot soldier to be tried with Franklin and the lieutenants, was convicted of one count of conspiracy to distribute and possess with intent to distribute a controlled substance (Count 1, Judgment of Simmons at 1; Verdict at 35-36) ; one count of RICO conspiracy (Count 2, Judgment of Simmons at 2; Verdict at 37) ; and three counts of distribution of PCP within 1,000 feet of a school (Counts 8, 10, and 30, Judgment of Simmons at 2; Verdict at 39-40). The jury acquitted Simmons of all murder, assault, and weapons charges (Counts 2, 129-32,148-49, and 158-59, Verdict at 37-39). In doing so, it found that the RICO conspiracy did not involve murder (Count 2, Verdict at 37). At sentencing, Franklin, Robinson, and Wilson were all sentenced to life in prison. Judgment of Franklin at 4; Judgment of Robinson at 3; Judgment of Wilson at 3. Blackson was sentenced to a total of 35 years of imprisonment, followed by 10 years of supervised release. Judgment of Blackson at 3-4. Simmons was sentenced to 22 years of imprisonment, followed by five years of supervised release. Judgment of Simmons at 3-4. D On appeal, appellants raise eleven discrete challenges to their convictions and sentences. First, all appellants argue that their cross-examination of the government’s key witness, Officer Donna Leftridge, was improperly limited in violation of the Confrontation Clause. Second, Blackson, Robinson, Simmons, and Wilson contend that they were prejudiced by the district court’s improper denial of their motion for severance. They argue that statements made by Franklin’s counsel during his opening and closing statements destroyed their ability to receive a fair and impartial trial. Third, all five appellants assert that the district court erred in its jury instructions concerning the RICO conspiracy charge. Specifically, they argue that the district court erred (1) in not instructing the jury that a conviction for RICO conspiracy requires a finding that a defendant participated in the operation or management of the enterprise; (2) in not instructing the jury that an “enterprise” must include an element of structure; and (3) in not instructing the jury that continuity is a necessary element of a “pattern of racketeering activity.” Fourth, Simmons contends that the prosecution improperly vouched for witness Roberta Moore. In doing so, Simmons claims, the government improperly invoked the authority of both the government and the court to support Moore’s veracity. Fifth, Simmons argues that the district court abused its discretion in denying his motion to strike testimony about his lifestyle that he deems “extraordinarily prejudicial.” Appellants’ Br. at 16. Sixth, Robinson contends that the district court erred in denying him permission to call two lay witnesses who were familiar with drug dealing and with the 18th and M Street area respectively. The district court ruled that the two witnesses’ testimony would amount to expert testimony under Rule of Evidence 702. Robinson contends, however, that the two witnesses were qualified to testify as lay witnesses based on their firsthand experience of drug sales and of the 18th and M area. Seventh, Wilson argues that the district court erred in denying his motion to suppress evidence obtained from a warrant-less search of his fianeée’s house. Wilson contends that the consent furnished to police by his fiancée was involuntarily procured. He argues that all evidence from the search was obtained unlawfully and should have been suppressed. Eighth, Franklin claims that the evidence presented at trial was insufficient to support the jury’s finding that he engaged in a continuing criminal enterprise. Specifically, he contends that insufficient evidence was presented at trial to prove that he organized, supervised, or managed five or more people. Ninth, Blackson claims that the district court erred in entering judgment against him for a count of which he was not convicted. Tenth, Simmons argues that the district court erred both procedurally and substantively in imposing an above-Guidelines sentence on him. Procedurally, he contends first that the district court impermissibly relied on his history of drug abuse in increasing his sentence and, second, that the district court failed to provide him with a written statement of the reasons for the variance. Substantively, he alleges that the district court failed to take into account aspects of his personal history that would have counseled in favor of a lower sentence. Finally, Robinson, Wilson, and Blackson contend that the district court based their sentences on erroneous factual findings. First, all three appellants claim the district court incorrectly attributed 30 or more kilograms of POP to each of them. Second, Wilson and Blackson contend that the district court incorrectly imposed a three-level Guideline enhancement for their role in the conspiracy. II Appellants contend their rights under the Confrontation Clause of the Sixth Amendment to the Constitution were violated in two respects: (A) when the district court limited cross-examination of undercover police officer Donna Leftridge by failing to order the government to disclose during trial information it had failed to turn over as required by Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963), regarding an ongoing investigation of Officer Leftridge; and (B) when the district court prohibited all questioning regarding Officer Leftridge’s alleged inappropriate social relationship with appellant John Franklin. Appellants maintain that they were consequently deprived of “all opportunities to impeach Leftridge’s credibility.” Appellants’ Br. at 23. The Sixth Amendment provides: “In all criminal prosecutions, the accused shall enjoy the right ... to be confronted with the witnesses against him.... ” U.S. Const, amend. VI. The Amendment guarantees a defendant the right to cross-examine the witnesses against him or her, and it is “the principal means by which the believability of a witness and the truth of his testimony are tested.” Davis v. Alaska, 415 U.S. 308, 315-16, 94 S.Ct. 1105, 39 L.Ed.2d 347 (1974). The district court must “give a defendant a ‘realistic opportunity to ferret out a potential source of bias.’ ” United States v. Davis, 127 F.3d 68, 70 (D.C.Cir.1997) (quoting United States v. Derr, 990 F.2d 1330, 1334 (D.C.Cir.1993)). “[A] criminal defendant states a violation of the Confrontation Clause by showing that he was prohibited from engaging in otherwise appropriate cross-examination designed to show a prototypical form of bias on the part of the witness, and thereby ‘to expose to the jury the facts from which jurors ... could appropriately draw inferences relating to the reliability of the witness.’ ” Delaware v. Van Arsdall, 475 U.S. 673, 680, 106 S.Ct. 1431, 89 L.Ed.2d 674 (1986) (quoting Davis v. Alaska, 415 U.S. at 318, 94 S.Ct. 1105). Our review of the district court’s legal conclusions regarding the Confrontation Clause is de novo. United States v. Carson, 455 F.3d 336, 362 (D.C.Cir.2006). A Appellants and their counsel did not learn until March 28, 2006, in the middle of the trial, that Leftridge had been suspended by the Internal Affairs Division (“IAD”) of the Metropolitan Police Department (“MPD”) due to an ongoing investigation. The day before, on March 27, prosecutors ex parte informed the district court that Leftridge had been suspended with pay by IAD due to [REDACTED] Leftridge had confirmed to the prosecutors that she did not know the basis of the investigation. The prosecutors advised the district court that Leftridge was under investigation [REDACTED] Leftridge was placed on the “Lewis List” of MPD officers who are under investigation. The district court concluded that the nature of the ongoing investigation of Leftridge was of limited relevance to her credibility or any potential bias but directed the prosecutors to disclose her status to defense counsel. The following day, March 28, 2006, the government disclosed to defense counsel, in writing, that: (1) IAD had suspended Leftridge with pay in early December 2005; (2) Leftridge was on the Lewis list; (8) Leftridge knew she was under investigation but not why or by whom; and (4) Leftridge was not under investigation by the U.S. Attorney’s Office for the District of Columbia. The government’s disclosure did not mention [REDACTED] Defense counsel sought additional disclosure pursuant to Brady, 373 U.S. 83, 83 S.Ct. 1194, and Giglio v. United States, 405 U.S. 150, 92 S.Ct. 763, 31 L.Ed.2d 104 (1972), or, failing that, an in camera review by the district court of the evidence supporting the government’s limited disclosure. The district court denied the request for additional disclosure, stating it had already conducted an in camera review. However, on March 30, 2006, the district court requested confirmation of the ex parte information [REDACTED] In United States v. Bagley, 473 U.S. 667, 105 S.Ct. 3375, 87 L.Ed.2d 481 (1985), the Supreme Court held that the withholding of potentially relevant impeachment evidence does not implicate the Confrontation Clause in the sense of “any direct restriction on the scope of cross-examination.” Id. at 678, 105 S.Ct. 3375. Instead, “the constitutional error, if any,” involves “the Government’s failure to assist the defense by disclosing information that might have been helpful in conducting the cross-examination.” Id. This latter duty arises under the Due Process Clause of the Fifth Amendment. See id. at 675, 105 S.Ct. 3375; see also Brady, 373 U.S. at 86, 83 S.Ct. 1194. As a plurality explained in Pennsylvania v. Ritchie, 480 U.S. 39, 107 S.Ct. 989, 94 L.Ed.2d 40 (1987), the Confrontation Clause did not create “a constitutionally compelled rule of pretrial discovery” of information that might be useful to the defense in preparing for trial. Id. at 52, 107 S.Ct. 989. Instead, “the right to confrontation is a trial right, designed to prevent improper restrictions on the types of questions that defense counsel may ask during cross-examination.” Id. (emphasis in original). This court has adopted the plurality’s holding. United States v. Tarantino, 846 F.2d 1384, 1415-16 (D.C.Cir.1988). Based on their access to the ex parte information of March 27, 2006 for the first time after filing their opening brief, appellants have added to their Confrontation Clause contention a Brady claim regarding the investigation of Leftridge. The Supreme Court held in Brady that “the suppression by the prosecution of evidence favorable to an accused upon request violates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution.” 373 U.S. at 87, 83 S.Ct. 1194. Thereafter the Court held that such disclosure is mandatory regardless of whether a defendant requests it, United States v. Agurs, 427 U.S. 97, 107, 96 S.Ct. 2392, 49 L.Ed.2d 342 (1976), and that impeachment evidence must also be disclosed, see Bagley, 473 U.S. at 676, 105 S.Ct. 3375; Giglio, 405 U.S. at 154, 92 S.Ct. 763. To determine whether there has been a Brady violation, courts apply a three-part test. “The evidence at issue must [1] be favorable to the accused, either because it is exculpatory, or because it is impeaching; that evidence must [2] have been suppressed by the [government], either willfully or inadvertently; and [3] prejudice must have ensued.” Strickler v. Greene, 527 U.S. 263, 281-82, 119 S.Ct. 1936, 144 L.Ed.2d 286 (1999). For prejudice to have ensued, there must be a “reasonable probability that, had the evidence been disclosed to the defense, the result of the proceeding would have been different,” id. at 280, 119 S.Ct. 1936 (internal quotation marks omitted), i.e., “the favorable evidence could reasonably be taken to put the whole case in such a different light as to undermine confidence in the verdict,” Kyles v. Whitley, 514 U.S. 419, 435, 115 S.Ct. 1555, 131 L.Ed.2d 490 (1995); see Bagley, 473 U.S. at 682, 105 S.Ct. 3375. Appellants contend that the district court erred by failing to order the government to make two required disclosures: (1) the subject matter of the investigation of Leftridge and (2) [REDACTED] This court has held that “to be ‘material’ under Brady, undisclosed information or evidence acquired through that information must be admissible.” Derr, 990 F.2d at 1336; see United States v. Johnson, 592 F.3d 164, 171 (D.C.Cir.2010); see also Wood v. Bartholomew, 516 U.S. 1, 6, 116 S.Ct. 7, 133 L.Ed.2d 1 (1995) (per curiam). Our review of the district court’s evidentiary rulings is for abuse of discretion. United States v. Lin, 101 F.3d 760, 768 (D.C.Cir.1996). With regard to non-disclosure of the subject matter of the investigation, the government persuasively maintains that there was no Brady violation because the undisclosed information would not have been admissible at trial, and appellants do not maintain that their knowledge of it could have led to admissible evidence. Although the defense might have sought to use the undisclosed information about the subject matter of the investigation to impeach Leftridge pursuant to Federal Rule of Evidence 608(b), the district court would properly have ruled such cross-examination improper because the subject matter of the internal investigation [REDACTED] would not have been probative of Leftridge’s truthfulness. Without additional evidence of wrongdoing beyond bald assertions [REDACTED], impeachment would have been based on unproven allegations. As this court stated in United States v. Morrison, 98 F.3d 619, 628 (D.C.Cir.1996), “the mere filing of a complaint [against a witness] is not probative of truthfulness or untruthfulness.” (emphasis in original) (internal quotation marks omitted). Additionally, had the defense sought admission of the subject matter of the investigation pursuant to Federal Rule of Evidence 404(b) to show Leftridge’s motive or bias, see generally United States v. Crowder, 141 F.3d 1202, 1206, 1209-10 (D.C.Cir.1998) (en banc), it is difficult to understand how the subject matter, rather than the fact of the existence of the investigation, would have assisted in portraying Leftridge as biased. Appellant William Simmons’ counsel cross-examined Leftridge about her suspension without pay and the suspension of her police powers as a result of the ongoing investigation, eliciting her admission to the suspension but also her denial of knowledge of the basis for the investigation. Presumably, based upon her suspension, Leftridge could have been motivated to testify falsely against appellants in order to curry favor with the government. But the fact that she was being investigated at all provided that potential motive. Even assuming information about the subject matter of the investigation was probative of bias, the district court would properly have excluded cross-examination pursuant to Rule 403 because “its probative value [wa]s substantially outweighed by the danger of unfair prejudice.” Fed.R.Evid. 403. As the district court concluded, the “prejudice to this officer given the uncertainty of the [allegations] is quite high, the prejudice to her career and her credibility is quite high.” Mar. 27, 2006 Ex Parte Tr. at 10. That risk of prejudice would have substantially outweighed the minimal probative value of the evidence. By contrast, the undisclosed information [REDACTED] would have been admissible pursuant to Rule 404(b) to show motive and bias. See United States v. (Juan) Bowie, 232 F.3d 923, 930 (D.C.Cir.2000). [REDACTED] On direct examination Leftridge denied she had been told why she was under investigation and why her police powers had been suspended; on cross-examination she acknowledged that she believed she was under investigation by IAD. These statements do not rule out Leftridge’s knowledge [REDACTED] Despite Leftridge’s apparent knowledge [REDACTED], the government disclosed to the defense only that she was suspended by IAD and was “under investigation.” Defense counsel understood the disclosure to mean that the investigation was being conducted by IAD only, as evidenced, for example, by defense counsel’s cross-examination of Leftridge: “You are being investigated by the internal affairs division of the Metropolitan Police Department?” Apr. 5, 2006 AM Trial Tr. at 77. Upon obtaining access to sealed materials after filing then- opening brief, appellants contended in their reply brief that requiring Leftridge to admit [REDACTED] would have strengthened their argument to the jury that Leftridge’s testimony was biased due to an “incentive to curry favor with the government.” Reply Br. at 13-14, 16. This argument is compelling. [REDACTED] It is true that the government disclosed to the defense that the U.S. Attorney’s Office for the District of Columbia was not investigating Leftridge, thus lessening the potential desire for Leftridge to curry favor with the prosecutors who were conducting appellants’ prosecution. But this disclosure also implied, as defense counsel reasonably understood, [REDACTED] In any event, this aspect of the disclosure cannot excuse the government’s non-disclosure [REDACTED] The defense was entitled to information that would strengthen its impeachment of Leftridge, whom the defense viewed as a key government witness because she interpreted video and audio tapes of the defendants and also engaged in repeated undercover drug purchases with several defendants, including appellants (except Wilson). See United States v. (Walter) Bowie, 198 F.3d 905, 909 (D.C.Cir.1999). Given its relevance as impeachment evidence, the government had a duty under Brady to make a timely pretrial disclosure to the defense [REDACTED] See United States v. Pollack, 534 F.2d 964, 973 (D.C.Cir.1976). The district court, in turn, erred in limiting cross-examination of Leftridge by failing to order the government to disclose this admissible evidence to the defense during trial. The question remains whether the undisclosed evidence [REDACTED] was “material,” i.e., was there “a reasonable probability that the result of the trial would have been different if the suppressed [evidence] had been disclosed to the defense.” Strickler, 527 U.S. at 289, 119 S.Ct. 1936 (internal quotation marks omitted). The “materiality inquiry is not just a matter of determining whether, after discounting the inculpatory evidence in light of the undisclosed evidence, the remaining evidence is sufficient to support the jury’s conclusions.” Id. at 290, 119 S.Ct. 1936. Instead, a court must ask whether “the favorable evidence could reasonably be taken to put the whole case in such a different light as to undermine confidence in the verdict.” Kyles, 514 U.S. at 435, 115 S.Ct. 1555. As an initial matter, it is worth noting that a reasonable jury could easily have concluded that Leftridge [REDACTED] “would be careful not to worsen [her] predicament” by perjuring herself, see (Walter) Bowie, 198 F.3d at 909. Secondly, as appellants must concede, and as the district court found, much of Leftridge’s testimony was corroborated by physical evidence including video and audio tapes, and to the extent Leftridge testified to what was also demonstrated by physical evidence, her credibility would be unimpaired. See id. at 911. Thirdly, given the physical evidence corroborating much of Leftridge’s testimony, appellants cannot show materiality under Brady by claiming that any bias would have affected the entirety of her testimony. Instead, appellants must contend that Leftridge was careful to mislead the jury only where her testimony would not go beyond what the physical evidence demonstrated — a degree of tailoring that would appear implausible. In any event, we conclude, upon review of the likely effect of informing the jury of the undisclosed evidence [REDACTED], that there is not a reasonable probability that the result of the trial would have been different for any appellant. Leftridge testified regarding the drug and RICO conspiracies (Counts 1 and 2), of which each appellant was convicted; the continuing criminal enterprise (Count 3) of which Franklin was convicted; and the drug distribution counts of which Franklin, Black-son, Robinson, and Simmons were convicted. As regards the drug distribution counts, Franklin conceded his guilt, Wilson faced no charges, and Robinson did not contest the single count against him, where he is plainly visible on videotape. Therefore, only the drug distribution convictions of Blackson and Simmons could even theoretically be called into question through the impeachment of Leftridge with the undisclosed evidence. 1 As to the convictions of all appellants for drug conspiracy (Count 1) and RICO conspiracy (Count 2), and the conviction of Franklin for continuing criminal enterprise (Count 3), the nondisclosure [REDACTED] was not material. Each appellant was convicted of conspiracy to distribute and possess with intent to distribute one kilogram or more of phencyclidine (“PCP”), and 50 grams or more of cocaine base in violation of 21 U.S.C. §§ 846, 841(a)(1), 841(b)(l)(A)(iii), (iv). The volume of PCP distributed, 15-20 gallons— equivalent to 39-52 kilograms — -was proven through the testimony of Franklin’s supplier, Herbert Martin. Each appellant’s involvement was proven in multiple ways without Leftridge’s testimony. • Count 1. The government demonstrated the existence of the conspiracy largely through evidence from cooperating members of the M Street Crew, through wiretaps of Franklin’s cellphone, and through the physical evidence accumulated during Leftridge’s undercover buys. For instance, cooperator Ronnie Tucker identified Joseph Blackson, “Mike” Simmons, “Dee” Robinson, and “Shug” Wilson as selling drugs, and recognized John Franklin as the leader of the group. Tucker also testified that “we all sold drugs together. Besides that [we] watch each other’s back, make sure everybody was all right.” Apr. 24, 2006 PM Trial Tr. at 4-5. Similarly, cooperator Michael Abney testified that the M Street Crew would do “a variety of things” together including “selling drugs.” May 2, 2006 AM Trial Tr. at 9. He named Franklin as the leader, Blackson, Robinson, and Wilson as Franklin’s lieutenants, and Simmons as Franklin’s most loyal foot soldier. The wiretap, audio, and video evidence corroborated the testimony of the eooperators, who were impeached on cross-examination, and provided ample evidence of conspiracy. For example, according to the transcript of Franklin’s wiretapped cellphone call on August 11, 2003, Franklin told Tucker to buy PCP from Robinson rather than himself. And on the November 21, 2002 videotape recording, Leftridge bought PCP at 18th and M Streets from someone (not visible on the recording) who identified himself as “Joe” and who eventually gave her his cellphone number. Later, on January 7, 2003, when Leftridge came back to the area to buy from “Joe,” she instead bought PCP from John Franklin, who is' clearly visible on videotape, and referred to “Joe” as his brother. When Franklin exited Leftridge’s car, he yelled “Mike” and another individual came to the passenger window and delivered a vial. That individual’s face is plainly visible. On April 10, 2003, following a cellphone conversation with Franklin, that same individual is seen on videotape getting into the car to deliver drugs to Leftridge. Again, his face was plainly visible, and a juror would have been able to recognize him in both instances as Simmons. The above represents only a small part of the evidence demonstrating a conspiracy under 18 U.S.C. § 846. Even were Leftridge’s testimony discredited by the undisclosed evidence, there is not a reasonable probability of a different verdict on Count 1 for any appellant. • Count 2. Similarly, each appellant was convicted of conspiracy under RICO, 18 U.S.C. § 1962(d). Pursuant to the district court’s instructions, the jury had to find: (1) an enterprise — in this case an illegal association in fact — existed; (2) the enterprise engaged in or affected interstate commerce; (3) individual defendants knowingly and intentionally agreed with another person to conduct the affairs of the enterprise; and (4) each defendant knowingly and willfully agreed that he or some other member of the conspiracy would commit at least two racketeering acts. See infra Part IV. Elements one and three appear to have been proven primarily through cooperators. For instance, Abney described the structure of the M Street Crew, and Tucker described each of the five appellants as “members” of M Street. Leftridge’s testimony as to individual buys added little information about the M Street Crew’s structure, but the physical evidence accompanying her buys did corroborate the cooperators’ testimony. For example, on March 26, 2003 Blackson told Leftridge that “everybody ... buy from us.” Mar. 26, 2003 Wiretap Tr. at 4. As to element four, impeachment of Leftridge’s testimony with the undisclosed information would have done nothing to undermine the evidence that each appellant committed two or more racketeering acts. As noted, Franklin conceded his guilt as to all of the drug distribution charges. Wilson was not charged with drug distribution, so the two racketeering acts of which the jury found him guilty could not have involved Leftridge’s undercover buys. Robinson’s guilt was plain on videotape showing the May 21, 2003 sale with which he was charged, his sole possible racketeering act related to Leftridge’s undercover work. Blackson is readily visible on videotape of the March 26, 2003 undercover buy and gave Leftridge his cellphone number and referred to himself as “Joe” during the November 21, 2002 buy, effectively identifying himself as the seller. Simmons is twice seen on videotape delivering drugs to Leftridge; he conceded guilt as to the April 10, 2003 buy. Again, the above are only examples of the evidence of guilt that render a different result on Count 2 highly improbable even were the jury, based on the undisclosed evidence, to discount Leftridge’s testimony. • Count 3. Franklin was charged with being the principal administrator, organizer, or leader of a continuing criminal enterprise, in violation of 21 U.S.C. § 848. This count required the government to prove that he supervised five or more persons. Evidence unrelated to Leftridge’s testimony showed that Franklin supervised five or more people. See infra Part IX. Although appellants suggest that Leftridge provided the only evidence that Franklin and Blackson worked together and that Franklin directed other members of the Crew to deliver PCP to a buyer, this ignores the physical videotape evidence of Leftridge’s buys. For instance, on January 7 and April 10, 2003, Simmons’ face is visible on videotape as he delivered drugs immediately after Leftridge spoke to Franklin. And on January 22, 2003, after Leftridge contemporaneously identified “Joe” [Blackson] and asked him for a “whole one,” Franklin got into Leftridge’s car, took Leftridge’s money, and asked her why “Joe” gave her á good price and later, “what’s up with you and Joe ... what’s up with you and my little brother?” Jan. 22, 2003 Wiretap Tr. at 1, 3, 6. The physical evidence thus demonstrates, without Leftridge’s testimony, that Simmons acted as Franklin’s runner and that Blackson and Franklin worked together. Undermining Leftridge’s credibility through impeachment with the undisclosed evidence would therefore have had no impact on Franklin’s conviction of Count 3. Although Franklin challenges the sufficiency of the evidence that he managed at least five people, see infra Part IX, his Count 3 conviction was not based in large part on Leftridge’s testimony and, to the extent her testimony related to the Count 3 charge, it is corroborated by physical evidence. 2 Joseph Blackson was convicted of eleven counts of drug distribution, from November 21, 2002 (Count 6) through July 16, 2003 (Count 42). According to the government’s brief, and uncontested in appellants’ reply brief, Blackson acknowledged his guilt of distribution on March 26 and April 30, 2003 (Counts 27 and 33). Further, neither at trial nor on appeal has Blackson contested the identification of his voice with respect to the recorded undercover buys by Leftridge or the wiretapped cellphone calls. The transcripts of those recorded buys and calls identify Blackson as selling drugs to Leftridge on eight occasions (Counts 9, 10, 13, 16, 19, 23-24, and 42). During the November 21, 2002 sale (Count 6), Blacksoris voice is audible and matches the voice on the audiotape for March 26, 2003 (Count 27), a count of which Blackson acknowledged guilt. And during the same November 21, 2002 sale, Blackson gave Leftridge his cellphone number and identified himself as “Joe.” Other recorded evidence also supports Blacksoris convictions.' On January 15, 2003 (Count 9), Blackson noted he had been “on house arrest for a minute,” Jan. 15, 2003 Wiretap Tr. at 2, which corresponded with his arrest on January 3, 2003. On several occasions, Leftridge greeted Blackson by name (Counts 16, 23, and 42), and she frequently identified Blackson contemporaneously to her supervisors before or after buying drugs (Counts 10,13, and 24). As these examples indicate, the evidence against Blackson on drug distribution was overwhelming, and there is no reasonable probability that any of the distribution verdicts would have been different had Leftridge’s testimony been impeached by the undisclosed evidence. 3 Appellants contend that impeachment of Leftridge with the undisclosed evidence would have especially undermined the evidence against William Simmons for distribution of PCP within 1,000 feet of a school on January 7 and 22 and April 10, 2003 (Counts 8, 10, and 30). However, Simmons is visible on videotape handing drugs to Leftridge on April 10, 2003. Simmons also is visible on videotape of the sale on January 7, 2003, when Franklin exited the car, shouted “Mike,” and Simmons appeared at the passenger door to deliver a vial of drugs to Leftridge. Appellants note that on January 7 and April 10 the police contemporaneously had difficulty identifying Simmons. But this is unremarkable because Leftridge testified that at the time of the April 10, 2003 buy she had not yet heard of Simmons. It is a different question whether there is a reasonable probability that a jury, viewing Simmons in the courtroom and on videotape, would not have convicted him of Counts 8, 10, and 30 had Leftridge’s testimony been impeached by the undisclosed evidence. Given the unambiguous physical evidence, there is not such a reasonable probability. This is true even as to the January 22, 2003 buy (Count 10), which is a closer call because the face of the individual on videotape delivering the drugs to Leftridge was partially obscured by a ski mask. Even without the videotape and Leftridge’s testimony, however, the evidence showed: (1) During that buy, Franklin stated that the person about to deliver the PCP was his “cousin,” “Mike,” Jan. 22, 2003 Wiretap Tr. at 6; (2) On April 10, 2003, the next time he saw Leftridge, Simmons acknowledged that he had “done some business” with her before “round on 18th Place,” Apr. 10, 2003 Wiretap Tr. at 3; and (3) cooperators testified that Simmons was Franklin’s runner. Although the credibility of the cooperators was impeached, their identification of Simmons as Franklin’s runner is supported by evidence that Simmons delivered drugs to Leftridge on two other occasions. Leftridge’s testimony that Simmons delivered the drugs on January 22 was not inconsistent with any of the physical evidence. Moreover, the evidence that Simmons was Franklin’s runner is secondary to the most damning evidence against Simmons on Count 10: the videotape of Franklin’s contemporaneous identification of his cousin, “Mike.” With that evidence — alongside the evidence of Simmons’ previous history as Franklin’s runner and two other deliveries to Leftridge — there is not a reasonable probability that a jury would have failed to convict Simmons of the January 22, 2003 sale if Leftridge’s testimony had been impeached by the undisclosed evidence. Accordingly, appellants cannot succeed on either their first Confrontation Clause contention or their Brady claim. The undisclosed evidence regarding the investigation of Leftridge was not “material” under Brady. And, in view of the overwhelming evidence of appellants’ guilt, any error by the district court in limiting cross-examination by failing to order the government to provide the defense with the undisclosed evidence regarding the investigation of Leftridge was harmless beyond a reasonable doubt, see Chapman v. California, 386 U.S. 18, 24, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967). B Appellants contend that their rights under the Confrontation Clause were also violated because the district court improperly prohibited them from questioning Leftridge about an inappropriate social relationship that she had with appellant John Franklin while she was working undercover in the investigation of the M Street Crew. During the trial, on March 30, 2006, Franklin’s counsel made an ex parte proffer to the district court that Franklin claimed that he and Leftridge had a social relationship beyond the scope of her role as an undercover officer. Franklin claimed that he and Leftridge had met about six times: For instance, they had dinner at Union Station, they went to the movies together on at least one occasion, and Franklin had loaned Leftridge $1,000, which she repaid approximately one week later. In support of the proffer, Franklin’s counsel stated that Franklin was willing to testify under oath out of the presence of the jury about the social contacts. Further, his counsel pointed to purportedly corroborating evidence, stating that wiretap recordings indicated Franklin had seen Leftridge in her personal car; recordings of Franklin asking Leftridge what car she was driving showed, counsel asserted, that there had been contact beyond the scope of the undercover investigation. Franklin’s counsel argued this evidence would “tend to show that [Leftridge] is not reliable,” or “at a minimum [had] terribly bad judgment,” and that “perhaps there’s some kind of bias to protect herself at this point should those allegations be true.” Apr. 3, 2006 AM Trial Tr. at 4. After the district court informed the prosecutor of Franklin’s proffer, the prosecutor reported to the district court that Leftridge had “flatly, categorically denie[d]” Franklin’s allegations and would deny them on the witness stand. Mar. 30, 2006 PM Trial Tr. at 20. The district court ruled it would not allow any cross-examination of Leftridge about the alleged social relationship. While not assessing the credibility of the allegations, the district court reasoned that whether Leftridge exercised bad judgment in having a social relationship with a target “doesn’t go directly to her credibility or her truthfulness.” Apr. 3, 2006 AM Trial Tr. at 6. In the district court’s view, because “everything to which [Leftridge] is testifying is supported by video and audio tape,” little room was left to impeach her credibility. Id. Our review is for abuse of discretion, see Lin, 101 F.3d at 768, not for plain error, as the government suggests, because the district court cited authority addressing limitations on cross-examination — namely Lin and United States v. Whitmore, 359 F.3d 609 (D.C.Cir.2004)— making it “apparent from the context,” Fed.R.Evid. 103(a)(1), that the defense was making a Confrontation Clause claim. The Supreme Court has instructed with regard to cross-examination to expose potential bias of a prosecution witness, that “trial judges retain wide latitude insofar as the Confrontation Clause is concerned to impose reasonable limits on such cross-examination based on concerns about, among other things, harassment, prejudice, confusion of the issues, the witness’ safety, or interrogation that is repetitive or only marginally relevant.” Delaware v. Van Arsdall, 475 U.S. at 679, 106 S.Ct. 1431. See Delaware v. Fensterer, 474 U.S. 15, 20, 106 S.Ct. 292, 88 L.Ed.2d 15 (1985). So too, in Lin, this court required defense counsel to “have a reasonable basis for asking questions on cross-examination which tend to incriminate or degrade the witness and thereby create an unfounded bias which subsequent testimony cannot fully dispel.” 101 F.3d at 768 (internal quotation marks omitted). As a general matter, “the questioner must be in possession of some facts which support a genuine belief that the witness committed the offense or the degrading act to which the questioning relates.” Id. (quoting United States v. Fowler, 465 F.2d 664, 666 (D.C.Cir.1972)); see Whitmore, 359 F.3d at 622. Because testimony that Leftridge had an inappropriate social relationship with the target of an investigation she was helping to conduct would degrade her, the issue is whether the district court impermissibly impinged on appellants’ confrontation rights in concluding that the defense did not have a reasonable basis for such cross-examination. The parties disagree about whether the defense proffer provided a “reasonable basis” to allow cross-examination of Leftridge and whether Lin applies. In Lin, the defendant sought to impeach a government witness, Guan Huan Chen, through cross-examination about Chen’s involvement in a gambling business located in Chinatown. 101 F.3d at 767. Lin alleged that Chen was biased against him because Chen sought “to remove Lin from the Chinatown gambling scene.” Id. The district court “offered to hold a hearing on the matter outside the presence of the jury,” but when defense counsel refused, the district court ruled that the proffer by defense counsel was not, standing alone, enough to permit the defendant “to initiate a highly prejudicial line of cross-examination.” Id. This court affirmed. Recognizing that “[t]he questioning that [defense counsel] sought to pursue would imply that the [prosecution’s] witness was involved in illegal activities, and thus would have been highly prejudicial,” this court concluded that defense counsel had not met his burden to “show that the proposed line of cross-examination followed a lead reasonably suggested by other facts in evidence.” Id. at 768. The court noted the defense refusal to agree to a hearing outside the presence of the jury and the district court’s willingness to hear other evidence supporting the defense theory. Id. Appellants point out that Franklin’s counsel offered more factual support for the cross-examination of Leftridge than did Lin’s counsel in seeking to cross-examine a government witness. Unlike Lin, Franklin was willing to testify outside the presence of the jury, and the defense proffered recorded conversations during which Franklin had asked Leftridge on two occasions about the type of car she was driving, independently indicating, according to his counsel, that Franklin knew about her personal car and not just the government car she used for undercover drug buys. The import of the tapes is not altogether clear; they may simply indicate that Franklin did not realize with whom he was speaking when Leftridge telephoned him and needed to know the identity of the car she was driving so he could tell one of the M Street Crew to give her a vial of drugs when she arrived on the scene. Although the district court understood counsel’s reference to late 2003 to refer to Leftridge’s request for the $1,000 loan, the government suggests on appeal that there is some uncertainty about when the alleged social relationship occurred. Of course, any uncertainty could have been explored and potentially resolved had the district court agreed to hear from Franklin outside the presence of the jury, and his testimony would have provided the district court with facts on which allowing cross-examination could turn. We need not decide whether Lin applies where a defendant agrees to testify under oath about facts supporting a proffered line of cross-examination. Assuming the district court erred in denying any cross-examination of Leftridge about an inappropriate social relationship, appellants cannot show the requisite prejudice. Unlike harmless error analysis, which focuses on the totality of evidence against a defendant, for Confrontation Clause purposes the “prejudice inquiry ... [focuses] on the particular witness, not on the outcome of the entire trial.” Delaware v. Van Arsdall, 475 U.S. at 680, 106 S.Ct. 1431. Even if the district court had concluded that there was a reasonable basis for cross-examining Leftridge about her alleged social relationship with Franklin, appellants fail to explain how the social relationship would be relevant to Leftridge’s penchant for truthfulness, as would be necessary to use the evidence pursuant to Federal Rule of Evidence 608(b). As the district court observed, bad judgment is not the same as untruthfulness. Similarly, had defense counsel cross-examined Leftridge about the alleged social relationship, the prosecutor had reported that Leftridge would deny its existence, and the defense would have been stuck with her denial because specific instances of untruthfulness are not provable by extrinsic evidence under Rule 608(b), see Whitmore, 359 F.3d at 622. Even if Leftridge admitted having dinner, going to the movies, and borrowing money from Franklin, much of her testimony was corroborated by the physical evidence, and she might have offered a reasonable explanation for the social relationship relating to her continuing viability as an undercover officer in the M Street Crew investigation. Similarly, had the defense sought admission of evidence of the social relationship pursuant to Rule 404(b) to demonstrate bias, because of Leftridge’s motive to curry favor with the government, it is unclear how this would assist the defense. Even if extrinsic evidence would have been admissible to prove the social relationship, Franklin’s counsel stated that Franklin would testify outside the presence of the jury only if his testimony could not be used against him at trial and, in view of Franklin’s admissions of drug sales with Leftridge, that Franklin did not intend to pursue the matter at trial. Absent an evidentiary basis, a properly instructed jury could not use the questions Leftridge was asked on cross-examination to infer bias. Cf. Morrison, 98 F.3d at 628; United States v. Gartmon, 146 F.3d 1015, 1026 (D.C.Cir.1998). For these reasons, assuming the district court erred in barring cross-examination of Leftridge about an inappropriate social relationship, appellants fail to show prejudice under the Confrontation Clause. With overwhelming evidence of appellants’ guilt, see supra Part II.A, any error in preventing this impeachment of Leftridge was harmless beyond a reasonable doubt. See Chapman, 386 U.S. at 24, 87 S.Ct. 824. To the extent appellants contend that the district court abused its discretion under the federal rules of evidence, any error is harmless because it would not have “had substantial and injurious effect or influence in determining the jury’s verdict,” Kotteakos v. United States, 328 U.S. 750, 776, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946). Ill The appellants other than John Franklin contend that the district court abused its discretion in denying their motions for severance of their tiñáis. In particular, they argue that the court’s refusal to grant severance after Franklin’s counsel conceded guilt on the drug distribution and communication facility counts prejudiced their right to a fair trial. Prior to his opening statement, Franklin’s counsel informed the court and other defense attorneys that Franklin intended to concede his guilt on the substantive drug distribution and communication facility counts. Several of these counts involved other defendants: Blackson was charged with Franklin with two of the PCP distribution counts (Counts 10 and 42); Robinson was charged with two PCP distribution counts and three communication facility counts (Counts 36, 58, 96, 101, and 103); Simmons was charged with three distribution counts (Counts 8, 10, and 30); and Wilson was charged with three communication facility counts (Counts 104-06).