Full opinion text
BRORBY, Circuit Judge. Defendants-appellants Carl Marshall, Clarissa Williamson, Edward Dryden, Jr., and Karen Parker (collectively “defendants”), were convicted of various drug related offenses. On appeal, they assert infirmities with their respective convictions and sentences. Our jurisdiction arises under 28 U.S.C. § 1291 and 18 U.S.C. § 3742(a). We affirm. BACKGROUND On May 6, 1993, a federal grand jury in Kansas City, Kansas, returned an eight count indictment charging seven individuals with conspiracy to distribute cocaine base, commonly referred to as “crack” cocaine, in violation of 21 U.S.C. § 846, as well as seven substantive counts of distributing cocaine base in violation of 21 U.S.C. § 841(a)(1). Count one, the conspiracy count, alleged a single continuing conspiracy among these seven individuals from “on or before January 1, 1986 ... to on or about October 31, 1991.” A joint trial involving the defendants and Mr. Haynes commenced on September 8, 1993, and on October 4, 1993, after a five week trial, the jury convicted the defendants on the conspiracy and substantive distribution counts. The jury, however, was unable to reach a unanimous verdict as to Mr. Haynes and the court declared a mistrial as to the charges against him. The government’s theory of the case, supported by evidence offered at trial, can be summarized as follows. In 1986, Mr. Marshall married Ms. Phyllis Harper, whom he had known since 1985. At the time they met, Ms. Harper had been dealing marijuana and PCP for over a decade. Mr. Marshall joined in his wife’s drug dealing operation and he expanded their distribution base to cover the ever-increasing crack cocaine market. Although their crack cocaine distribution began as a relatively small operation, the evidence revealed that in 1987, Mr. Marshall made approximately $10,000 to $15,000 per month in profits. While Ms. Harper and Mr. Marshall were experiencing professional success in their drug ventures, their personal relationship and their marriage were simultaneously failing. As a result, they decided to establish independent drug distribution networks. They recognized, however, that if they pooled their money, they would be able to purchase larger quantities of drugs from the same supplier, presumably at better prices. They decided it would be in both of their interests to do this, and they subsequently pooled their money when purchasing large volumes of cocaine from their primary suppliers in California. ' From 1987 until late September 1988, Mr. Marshall’s drug business was becoming increasingly profitable. To meet his buyers’ demands, he and his “employees” made numerous trips to California — in custom-designed vans with secret compartments — to make multiple kilogram purchases of powder cocaine. Upon returning to Kansas City, Mr. Marshall and his employees would “cook” the powder cocaine into crack that would then be sold to various buyers. In late September 1988, while Ms. Harper and Mr. Marshall were in California to make a buy, Mr. Dryden, a twenty-five year veteran of the Kansas City, Kansas, police force who was Mr. Marshall’s brother-in-law and who was involved in Mr. Marsháll’s drug operation, advised Mr. Marshall that the authorities were going to arrest Ms. Harper upon her return to California. Based on this information, changes to the itinerary and travel route were arranged, and Charles Marshall, Mr. Marshall’s brother, was given the responsibility for driving the cocaine back from California. Shortly thereafter, Ms. Harper was doused with gasoline and set on fire, resulting in her death. An investigation into her death commenced, and the scope of the investigation encompassed Mr. Marshall and potentially, his drug activities. In reliance on Mr. Dryden’s advice, Mr. Marshall decided to cease temporarily his drug operation until the investigation into Ms. Harper’s death died down. As a result, Mr. Marshall’s drug operations ceased business from the fall of 1988 until the spring of 1989, a period of seven months. During this time frame, Mr. Marshall enjoyed the fruits of his trade, spending much of his profits on women, poker, a taxi cab company and pleasure trips. After the seven-month hiatus, Mr. Marshall resumed his distribution operation with many of the same people working for him as had worked for him earlier. When Mr. Marshall resumed his operations in the spring of 1989, he was no longer dealing on the same scale as he had been before Ms. Harper’s death. His purchases from his California suppliers were reduced to one or two kilograms per trip. In October 1991, Mr. Marshalls operation was essentially out of business, as there was little money left to continue to sustain the businesses’ operations and Mr. Marshall’s own personal crack use and extravagant life-style. Mr. Marshall, the head of this drug operation, enlisted the services of each of the six other individuals charged in the indictment. The government’s theory on the conspiracy count was that each of these individuals was an active participant in his crack distribution ring. For example, Mr. Marshall headed the operation, purchased the cocaine from suppliers in California and directed the other participants. Mr. Dryden was enlisted for assistance with financial matters and, at least in the government’s view, for his help in avoiding detection by law enforcement personnel through his connections with the Kansas City police department. Therisa Ross, one of Mr. Marshall’s girlfriends, characterized Mr. Dryden as a “watchdog” for Mr. Marshall’s business. In that capacity, Mr. Dryden would run names and car licenses before trips to California, as well as warn the organization about possible busts on their return trips from California and warn everyone about investigations, including the investigation into Ms. Harper’s death, and possible sales to undercover officers. He also stored some of the monetary proceeds from the sales at his residence. In return for his assistance, Mr. Marshall would provide him with free crack “crumbs” that were created when Ms. McGee would cook the powder cocaine into crack. Mr. Dryden used these crumbs to support his own drug habit. Ms. Williamson was hired by Mr. Marshall in 1987 to cook the powder cocaine into crack, to store the cocaine at her residence, which was used as a base of operation, to assist in transporting the cocaine back from California and to sell and deliver most of the operations’ crack to its buyers. In exchange for her services, Mr. Marshall paid Ms. Williamson on a commission basis. Tina McGee, Mr. Marshall’s ex-wife and the mother of their son, was hired to perform many of the same functions Ms. Williamson did, including cooking the powder cocaine and storing it at her residence, which was also used as a base of operation. Unlike Ms. Williamson, however, Ms. McGee received a flat salary of $400 per week for her services, rather than a commission. Mr. Marshall also enlisted the services of two of his girlfriends, Ms. Ross and Ms. Parker, both of whom served as cookers and runners. After Ms. Ross and Mr. Marshall had a falling out, Ms. Parker assumed Ms. Ross’ duties in exchange for free use of a residence. Most of the seven substantive distribution counts alleged in the indictment were based on sales by Ms. Williamson and Mr. Marshall to undercover officers. These sales eventually led to the arrest of each of the seven named individuals, and ultimately resulted in the convictions forming the basis for the present appeals. DISCUSSION I. Challenges to the Defendants’ Convictions A. Constitutional Issues 1. Ms. Parker, Mr. Dryden and Mr. Marshall assert the prosecution improperly exercised one of its peremptory challenges to excuse a potential juror, an African-American woman, from the-venire. They claim this challenge was made “because of’ the venire-person’s race, which is an impermissible race-based use of a peremptory challenge, in violation of principles of equal protection under Batson v. Kentucky, 476 U.S. 79, 106 S.Ct. 1712, 90 L.Ed.2d 69 (1986), and its progeny. See United States v. Johnson, 941 F.2d 1102, 1105 & n. 3 (10th Cir.1991). The ultimate issue of intentional discrimination under Batson is a question of fact and thus, we review the district court’s finding under the clearly erroneous standard. See United States v. Johnson, 4 F.3d 904, 913 (10th Cir.1993), cert. denied, — U.S. -, 114 S.Ct. 1082, 127 L.Ed.2d 398 (1994). The defendants’ Batson claim in this ease arose from the following circumstances. During jury selection, a female African-American juror, Ms. Roland, was selected from the venire as a potential juror. After voir dire, the prosecutor, herself an African-American, elected to strike Ms. Roland peremptorily. Counsel for Mr. Haynes, on behalf of all defendants, requested that the court conduct a Batson inquiry. The court agreed, and the prosecution then offered three reasons for striking Ms. Roland: (1) she had a specific recollection of having met Ms. Parker, albeit twenty years ago for five minutes; (2) she knew one of the prosecution’s witnesses, Jesse Gray, who was a police officer, from school and from church; and (3) she had a cousin and an aunt who had been involved with illegal drugs. Mr. Harris, joined by all defendants, argued to the court that those reasons were “not satisfying.]” After considering the parties’ respective arguments, the court expressed its belief that this was “a fairly close call ... a very close call,” but nonetheless overruled the objection. The court also determined that the prosecution had challenged all other prospective jurors who, like Ms. Roland, knew police officers who were scheduled to testify for the prosecution. Finally, the trial court relied on its personal experience that “the Assistant United States Attorneys for the District of Kansas ... do not routinely strike members of minority groups,” although the trial judge expressed some concern over whether it was even proper to consider this information. During the remainder of jury selection, the prosecution elected not to strike peremptorily Ms. Stallings, another African-American female who had been called as an alternate juror. While Ms. Stallings had a friend on the police force, she did not know any of the prosecution’s potential witnesses. Moreover, while she had relatives involved with drugs, she categorically stated she had a negative attitude towards drugs. The primary argument advanced by the defendants in support of their claim that the district court committed clear error in finding that there was no intentional discrimination is, in essence, that the prosecution elected to strike Ms. Roland but not Ms. Stall-ings. In Batson, the Court held the Equal Protection Clause prohibits the prosecution from exercising its peremptory challenges in a racially discriminatory manner. Batson, 476 U.S. at 85-86, 106 S.Ct. at 1716-17. While the initial burden of establishing a Batson violation is on the defendant, United States v. Hartsfield, 976 F.2d 1349, 1356 (10th Cir.1992) (citing Powers v. Ohio, 499 U.S. 400, 404-05, 111 S.Ct. 1364, 1367, 113 L.Ed.2d 411 (1991)), cert. denied, — U.S. -, 113 S.Ct. 1344, 122 L.Ed.2d 727 (1993), meeting that burden is irrelevant in cases, such as this, where “the prosecutor offers a race-neutral explanation for [the use of] the peremptory challenges and the trial court rules on the ultimate factual issue of whether the prosecutor intentionally discriminated.” Johnson, 941 F.2d at 1107 (citing Hernandez v. New York, 500 U.S. 352, 359, 111 S.Ct. 1859, 1866, 114 L.Ed.2d 395 (1991)). In the present case, the reasons advanced by the prosecution as to why it elected to strike Ms. Roland are facially race-neutral. The proffered reasons related to the prospective juror knowing the defendant, being acquainted with a witness, and being familiar with the subject matter of the trial. These reasons are clearly unrelated to the race of the venireperson, and this is sufficient under Hernandez and its progeny to constitute a facially race neutral explanation. See Hernandez, 500 U.S. at 359-60, 111 S.Ct. at 1866. Moreover, although the district court believed this was a “close case,” it concluded no Batson violation had occurred. While the defendants may not believe the prosecutor’s reasons were satisfactory, that does not change the fact that those reasons are legally sufficient under applicable precedent to dispel any claim of an equal protection violation. Furthermore, there has been no showing regarding how or why these reasons were pre-textual. In the absence of any evidence of pretext, we simply have no basis for overturning the district court’s finding that there was no intentional discrimination in the jury selection. Our conclusion that no Batson violation occurred is bolstered by the fact the prosecution retained an African-American on the jury. We have previously noted that “although the mere presence of members of a certain race on the final jury does not automatically negate a Batson violation, ... it can be a relevant factor, particularly when the prosecution had the opportunity to strike them.” United States v. Esparsen, 930 F.2d 1461, 1468 (10th Cir.1991), cert. denied, 502 U.S. 1036, 112 S.Ct. 882, 116 L.Ed.2d 786 (1992); see also United States v. Marin, 7 F.3d 679, 686 & n. 4 (7th Cir.1993), cert. denied, - U.S. -, 114 S.Ct. 739, 126 L.Ed.2d 702 (1994); United States v. Mixon, 977 F.2d 921, 923 (5th Cir.1992); United States v. Allison, 908 F.2d 1531, 1537 (11th Cir.1990). For the reasons expressed above, we conclude no violation occurred. 2. Ms. Williamson next asserts her conviction must be vacated because she received ineffective assistance of counsel during the trial. The gravamen of her claim is that trial counsel’s closing argument to the jury amounted to a concession of her guilt. She asserts this conduct resulted in a breakdown of the adversarial process and a denial of her Sixth Amendment right to counsel. After the prosecution rested its case-in-chief, Ms. Williamson elected to testify in her own defense. During direct examination, Ms. Williamson admitted to buying and selling drugs for personal use. On cross-examination, she stated she believed two of the undercover officers were lying and a third officer was only telling the “partial truth” regarding her involvement in the overall conspiracy. During closing argument, Ms. Williamson’s attorney argued to the jury that although Ms. Williamson was an admitted drug user who bought from, and associated with, known drug dealers, the evidence did not demonstrate that she herself was a coconspirator. During the course of his closing argument, counsel also stated, in reference to several of the government’s witnesses, that “I’m not going to accuse all of these people of lying. I think some of them were and some of them were not.” Counsel also stated, in reference to the testimony of three undercover officers who allegedly purchased drugs from Ms. Williamson forming the basis for substantive distribution counts, “I’m not disputing the fact that this all happened.” Counsel made these statements in spite of Ms. Williamson having testified she believed the three officers were lying. Counsel further stated he believed these officers testified as to what actually happened. During rebuttal argument, the prosecutor noted that defense counsel’s argument was interesting because he said some things “that his client would appear to disagree with.” Ms. Williamson was thereafter convicted. The Sixth Amendment provides “[i]n all criminal prosecutions, the accused shall ... have the assistance of counsel for his defence.” U.S. Const. amend. VI. While a defendant must ordinarily prove deficient performance by counsel coupled with a showing of prejudice in order to prevail on an ineffective assistance of counsel claim, Strickland v. Washington, 466 U.S. 668, 687, 104 S.Ct. 2052, 2064, 80 L.Ed.2d 674 (1984), there is a narrow class of cases where the particular circumstances “are so likely to prejudice the accused that the cost of litigating their effect in a particular case is unjustified.” United States v. Cronic, 466 U.S. 648, 658, 104 S.Ct. 2039, 2046, 80 L.Ed.2d 657 (1984) (footnote omitted). If a defendant can prove such circumstances actually existed, prejudice will be presumed. Id. at 659-62, 104 S.Ct. at 2047-49. There is no question but that the sort of conduct alleged here, i.e., the admission by counsel of his client’s guilt to the jury, represents a paradigmatic example of the sort of breakdown in the adversarial process that triggers a presumption of prejudice. See, e.g., United States v. Swanson, 943 F.2d 1070, 1074 (9th Cir.1991); Jones v. State, 110 Nev. 730, 877 P.2d 1052, 1056-57 (1994) (quoting Brown v. Rice, 693 F.Supp. 381, 396 (W.D.N.C.1988), cert. denied, 495 U.S. 953, 110 S.Ct. 2220, 109 L.Ed.2d 545 (1990)). Whether such an admission actually occurred is necessarily fact-intensive. The focus must be on whether, in light of the entire record, the attorney remained a legal advocate of the defendant who acted with “‘undivided allegiance and faithful, devoted service’ ” to the defendant. See Osborn v. Shillinger, 861 F.2d 612, 624 (10th Cir.1988) (quoting Von Moltke v. Gillies, 332 U.S. 708, 725, 68 S.Ct. 316, 324, 92 L.Ed. 309 (1948)). Applying these principles to this case, we first note that regardless of how one characterizes defense counsel’s statements, it is clear they do not amount to the types of statements recognized in other cases that have been held to constitute a concession of guilt. See, e.g., Swanson, 943 F.2d at 1071, 1074 (defense counsel’s statements during closing argument conceding there was “no reasonable doubt” that his client was the perpetrator and that there was “no reasonable doubt” as to an essential element of the offense charged constituted a concession of guilt); Francis v. Spraggins, 720 F.2d 1190, 1193-94 & n. 7 (11th Cir.1983) (statement by defense counsel during closing argument in guilt phase of a capital trial that “I think he committed the crime of murder” constituted a concession of guilt), cert. denied, 470 U.S. 1059, 105 S.Ct. 1776, 84 L.Ed.2d 835 (1985); Jones, 877 P.2d at 1055 (statement during closing argument that “the evidence shows beyond a reasonable doubt that the defendant” was the perpetrator was a concession of guilt); State v. Harbison, 315 N.C. 175, 337 S.E.2d 504, 505 (1985) (statement by defense counsel that “I don’t feel that [the defendant] should be found innocent” was a concession of guilt), cert. denied, 476 U.S. 1123, 106 S.Ct. 1992, 90 L.Ed.2d 672 (1986). While counsel’s statements in this case may have contradicted one aspect of the defendant’s own testimony, this is a far cry from a statement by counsel that there was no reasonable doubt Ms. Williamson was a member of this conspiracy, or that counsel believed Ms. Williamson was a coeonspirator. To the contrary, counsel’s closing argument is replete with argumentative statements demonstrating counsel’s adversarial representation of Ms. Williamson’s interests before the jury. Moreover, because the statements in question are not the functional equivalent of a concession of guilt, much of the reasoning underlying that fine of authority is simply inapposite. Without a concession of guilt, concerns over conflicts of interest, lessening the burden of proof beyond a reasonable doubt and impermissible pleas of guilty, do not factor into the equation. The record of counsel’s closing argument demonstrates counsel’s primary concern was to point to the absence of any evidence linking Ms. Williamson to this drug conspiracy. Counsel specifically asked the jury to pay attention to the conspiracy instructions, to focus on the fact that while Ms. Williamson was a conceded drug user who supported her habit by buying drugs from Mr. Marshall, these facts do not automatically make her a coconspirator, to remember the testimony that Ms. Williamson went on a trip to California to buy furniture and not as part of a “drug run,” to consider inconsistencies in the testimony of other witnesses, and to consider carefully the credibility of Willie Myles, an informant. Counsel also acknowledged there was “no doubt” Ms. Williamson “did some things that were wrong,” referring to her admission of having purchased and used illegal drugs. Counsel concluded by stating “I think when you review all of the evidence, I think that you will find that Clarissa Williamson is not a conspirator, and I hope that you will return a verdict of not guilty.” An objective assessment of counsel’s representations reveals he did not cease to function as an advocate on behalf of Ms. Williamson. He argued to the jury both the evidence in the record and the evidence lacking in the record, as well as arguing the weight and the credibility of the witnesses and the evidence. Counsel also focused the jury’s attention on the jury instructions and conceded undisputed facts in the record when necessary. While the reasons for the statements to which Ms. Williamson bases her claim are not entirely clear from the record, they may simply have been recognitions of Ms. Williamson’s own statements attesting to her involvement in distributing narcotics to some of the undercover officers, statements corroborated by audio tape recordings. In a related vein, the Supreme Court has recognized “[experienced advocates since time beyond memory have emphasized the importance of winnowing out weaker arguments ... and focusing on one central issue if possible.” Jones v. Barnes, 463 U.S. 745, 751, 103 S.Ct. 3308, 3313, 77 L.Ed.2d 987 (1983) (discussing counsel’s duty to raise non-frivolous issues on appeal). This insight is equally applicable to closing arguments made at trial. Counsel, in the exercise of professional judgment, primarily focused on attempting to obtain an acquittal for his client on the conspiracy charge, rather than particular substantive distribution charges. Given the state of the evidence adduced at the trial, and the substance of counsel’s closing argument at trial, we are not persuaded that the isolated refusals to contradict certain testimony given by the prosecution’s witnesses undermined counsel’s otherwise ethically and constitutionally sufficient representation of Ms. Williamson. Therefore, we reject this claim of error. 3. Mr. Marshall and Mr. Dryden next assert their convictions are infirm because of a fatal variance between the allegations of conspiracy in the indictment and the proof of conspiracy offered at trial. They contend a fatal variance was created when the indictment charged a single, continuing conspiracy but the evidence at trial proved, in their view, two distinct conspiracies. They allege the seven-month hiatus between late September of 1988, when Ms. Harper was murdered and Mr. Marshall temporarily ceased his operations, and the spring of 1989, when Mr. Marshall resumed his operations, created a fatal variance because the indictment charged a single conspiracy but the evidence demonstrated two separate conspiracies, severed by the temporal hiatus of seven months. The ultimate questions of whether a variance existed, and whether it was fatal such that relief is required, are questions of law that we review de novo. See United States v. Cardall, 885 F.2d 656, 670 (10th Cir.1989). “[I]t is a fundamental precept of federal constitutional law that a ‘court cannot permit a defendant to be tried on charges that are not made in the indictment.’” Hunter v. New Mexico, 916 F.2d 595, 598 (10th Cir. 1990) (quoting Stirone v. United States, 361 U.S. 212, 217, 80 S.Ct. 270, 273, 4 L.Ed.2d 252 (I960)), cert. denied, 500 U.S. 909, 111 S.Ct. 1693, 114 L.Ed.2d 87 (1991). Case law recognizes two different types of variances, similar in kind and different in degree. The first type of variance, referred to as a simple variance, “occurs when the charging terms are unchanged, but the evidence at trial proves facts materially different from those alleged in the indictment.” United States v. Haddock, 956 F.2d 1534, 1548 (10th Cir.1992) (citations and internal quotations omitted); see also Dunn v. United States, 442 U.S. 100, 105, 99 S.Ct. 2190, 2193, 60 L.Ed.2d 743 (1979) (“A variance arises when the evidence adduced at trial establishes facts different from those alleged in an indictment.”). The second type of variance, known as a constructive amendment of the indictment, is “more dangerous” than a simple variance “because it actually modifies an essential element of the offense charged,” thereby “effectively altering] the substance of the indictment.” Hunter, 916 F.2d at 599. With respect to the prohibition against simple variances, which is at issue in this case, we note the mere fact that a variance occurred does not automatically warrant relief. “Where a simple variance exists, ‘convictions generally have been sustained as long as the proof upon which they are based corresponds to an offense that was clearly set out in the indictment.’” Hunter, 916 F.2d at 599 (citing United States v. Miller, 471 U.S. 130, 136, 105 S.Ct. 1811, 1815, 85 L.Ed.2d 99 (1985)). This follows from the fact that the prohibition against variances is designed to insure notice of the charges; thus, a variance, without more, will not warrant relief as long as the proof corresponds to an offense clearly charged in the indictment because the defendant will have had notice of that charge and cannot claim prejudice. But when the variance rises to the level of a “fatal” variance, relief is appropriate. See Hunter, 916 F.2d at 598-99. “A variance ‘is fatal only when the defendant is prejudiced in his defense because he cannot anticipate from the indictment what evidence will be presented against him or is exposed to the risk of double jeopardy.’ ” Haddock, 956 F.2d at 1548 (quoting Hunter, 916 F.2d at 599). A review of the evidence in this case demonstrates that the defendant has failed to establish a variance. Therefore, we reject this claim. In United States v. Roberts, 14 F.3d 502 (10th Cir.1993), we reviewed a simple variance claim in the context of determining whether, as in this case, the government’s proof established two separate conspiracies when the indictment charged only a single conspiracy. In rejecting this claim, we refused to adopt a per se rule that “ ‘lapses of time ... necessarily convert a single conspiracy into multiple conspiracies.’ ” Id. at 511 (quoting United States v. Maldonado-Rivera, 922 F.2d 934, 963 (2d Cir.1990), cert. denied, 501 U.S. 1211, 111 S.Ct. - 2811, 115 L.Ed.2d 984 (1991)); see also United States v. Russell, 963 F.2d 1320, 1322 (10th Cir.) (“[A] conspiracy, once instituted, continues to exist until it is abandoned, succeeds, or is otherwise terminated by some affirmative act.”), cert. denied, - U.S.-, 113 S.Ct. 280, 121 L.Ed.2d 207 (1992); United States v. Smith, 833 F.2d 213, 220 (10th Cir.1987) (“The fact that the conspiratorial object was postponed or slowed down does not unequivocally show that the conspiracy was terminated.”) (citation and internal quotations omitted). In Leavis, the Fourth Circuit recognized there are many legitimate reasons why a single conspiracy might deliberately experience a lull in its operations. The court stated: “[a] single overall agreement need not be manifested by continuous activity.” There are a host of reasons for a conspiracy [to import cocaine] to suspend active operations for a period: for logistical reasons, to escape detection, or even to afford its members an opportunity to spend their ill-gotten gains. Our focus must be not on the timing of the conspiracy’s operations, but on whether it functioned as an ongoing unit. Leavis, 853 F.2d at 218-19. We believe the reasoning in Leavis is sound, and applying that reasoning to this case, we cannot say the seven month hiatus here severed the single continuous conspiracy alleged in the indictment into two separate conspiracies. Therefore, no variance resulted. Several of the reasons advanced in Leavis for a hiatus in a conspiracy are fully applicable to the case at bar. For example, the primary reason for the postponement of Mr. Marshall’s operations was to escape detection. Additionally, Mr. Marshall and other coconspirators spent this time enjoying the fruits of their proceeds. Yet in the spring of 1989, the operations resumed with the same participants, the same conspiratorial objective and the same course of conduct. Under these circumstances, we believe the conspiracy still functioned as a single ongoing entity, and we will not denigrate the simple variance principle by finding a variance here based on the defendants’ own conduct in unilaterally suspending their activities to serve their own purposes. Furthermore, the defendants cannot reasonably claim they did not have notice of what the. government intended to prove at trial, which, as stated before, is the central purpose behind the prohibition against simple variances. See Hunter, 916 F.2d at 599. Accordingly, we find no error. B. Evidentiary Issues 1. Defendant Parker reasserts on appeal her claims that the evidence was insufficient to support the jury’s verdict convicting her on count six, the charge of aiding and abetting a distribution of cocaine base by Mr. Marshal, and count one, the conspiracy charge. At the close of the government’s case-in-chief, counsel for Ms. Parker joined in counsel for Mr. Haynes’ Fed.R.Crim.P. 29 motion for judgment of acquittal. Ms. Parker’s counsel further requested that in ruling on this motion, the court consider both counts applicable to her client. Ms. Parker thus preserved her right to renew on appeal the sufficiency of the evidence issues pertaining to counts one and six. In reviewing a challenge to the sufficiency of the evidence, we review the record de novo, see United States v. Grimes, 967 F.2d 1468, 1472 (10th Cir.), cert. denied, - U.S. -, 113 S.Ct. 355, 121 L.Ed.2d 269 (1992), “and ask only whether, taking the evidence&emdash;‘both direct and circumstantial, together with the reasonable inferences to be drawn therefrom’&emdash;in the light most favorable to the government, a reasonable jury could find the defendant guilty beyond a reasonable doubt,” United States v. Urena, 27 F.3d 1487, 1489 (10th Cir.) (quoting United States v. Hooks, 780 F.2d 1526, 1531 (10th Cir.), cert. denied, 475 U.S. 1128, 106 S.Ct. 1657, 90 L.Ed.2d 199 (1986)), cert. denied, - U.S. -, 115 S.Ct. 455, 130 L.Ed.2d 364 (1994). In order to conclude the evidence was insufficient, as a matter of law, to support a conviction, “we must find that no reasonable juror could have reached the disputed verdict.” United States v. Hoenscheidt, 7 F.3d 1528, 1530 (10th Cir.1993). a. Ms. Parker asserts the evidence against her as to the aiding and abetting count is insufficient to demonstrate how she willfully associated herself with a criminal venture. She asserts Officer Crockett’s testimony merely places her at the scene of a drug deal without showing any active participation in a criminal undertaking. The government disagrees, and relies on the trial testimony of Kim Crockett, an undercover officer who participated in the controlled buy that formed the basis for count six of the indictment. We recently discussed the government’s burden of proof to support a conviction for aiding and abetting under 18 U.S.C. § 2. To support a conviction under this statute, the government must prove, beyond a reasonable doubt: (1) that the defendant associated herself with a criminal venture; (2) that the defendant participated in the venture as something she wished to bring about; (3) that she sought by her actions to make it succeed; and, lastly, (4) that the proof establishes the commission of the offense by someone and the aiding and abetting by the defendant so charged. United States v. Hanson, 41 F.3d 580, 582 (10th Cir.1994) (citing United States v. Yost, 24 F.3d 99, 104 (10th Cir.1994)). It is imperative that the government demonstrate the defendant “willfully associate^] [herself] with the criminal venture and [sought] to make it succeed through some action on [her] part.” Hanson, 41 F.3d at 582-83 (citations omitted); see also Esparsen, 930 F.2d at 1470; Roth v. United States, 339 F.2d 863, 865 (10th Cir.1964). In this case, Officer Crockett testified he contacted Mr. Myles, an informant with whom he was working, and he asked him to arrange a controlled buy of crack cocaine from Mr. Marshall. Mr. Myles agreed and arranged to have Mr. Marshall meet with Officer Crockett on June 20, 1990. That evening, Officer Crockett drove to a prearranged location and met Mr. Myles. The two men then waited for Mr. Marshall to arrive. When Mr. Marshall arrived, Officer Crockett observed a woman, whom he knew to be Ms. Parker, in the passenger seat of Mr. Marshall’s car. At that time, Mr. Myles and Officer Crockett entered the back seat of Mr. MarshaH’s car and prepared to make the controlled buy. Mr. Marshall reached into a pouch he was holding in his hand and removed two aluminum foil packages. He then handed the packages between the seats to Officer Crockett. Upon opening the packages, Officer Crockett observed “beige rock like substances, which appeared to be crack cocaine” in each package. Officer Crockett then placed $2,800 in Mr. Marshall's hand, and told him “there’s 28.” Mr. Marshall handed this money to Ms. Parker and told her to count it and make sure it was all there, which she did. Officer Crockett stated he personally observed Ms. Parker count the money. He also testified Ms. Parker never said anything, but that she remained inside the car during the time when the deal was taking place, and that this transaction occurred within her view. After this exchange, Officer Crockett asked Mr. Marshall to step out of the ear so he could ask him privately for his pager number so in the future, he could contact him directly, rather than having to use Mr. Myles as an intermediary. In fact, the reason Officer Crockett asked Mr. Marshall to step out of the ear was because this undercover búy was being videotaped and Officer Crockett wanted to get a picture of Mr. Marshall on tape. Mr. Marshall then gave Officer Crockett two pager numbers, which essentially concluded the deal forming the basis for count six. We agree with the general proposition that mere presence at the scene of a drug transaction, without more, is insufficient to support a conviction for aiding and abetting. See Hanson, 41 F.3d at 582-83. In this case, however, Officer Crockett’s testimony is sufficient to support a finding that Ms. Parker willfully associated herself with Mr. Marshall’s distribution of a controlled substance. Moreover, while Ms. Parker’s presence, standing alone, cannot support a conviction for aiding and abetting, it is certainly probative evidence that the jury may consider in determining whether she was guilty of the offense charged. There was testimony she was present during a drug transaction taking place at night, that the transaction occurred within her line of sight and that she counted a sum of money total-ling $2,800. In United States v. Harper, 579 F.2d 1235 (10th Cir.), cert. denied, 439 U.S. 968, 99 S.Ct. 459, 58 L.Ed.2d 427 (1978), we rejected a challenge to the sufficiency of the evidence to support a conviction for aiding and abetting, and in so holding, we stated “[d]efendant’s knowledge and participation are to be inferred from ... other testimony as to the amounts of money given him.” Id. at 1239. In that case, we deemed $600, coupled with the existence of other facts, sufficient to support an inference that the defendant had the requisite knowledge of illegal activity. The same can certainly be said for the $2,800 involved in this case. When all of this evidence is viewed in the light most favorable to the government, we believe it is sufficient to permit the jury to infer Ms. Parker actively and willfully associated with, and participated in, a criminal venture. We also find the evidence sufficient to support a finding that her conduct in counting the money to make sure it was the proper amount was an effort by her to make this venture successful. In short, there was sufficient evidence to permit a finding that Ms. Parker was not simply present at this scene by happenstance, as she asserted at trial. At its core, Ms. Parker seeks to challenge a credibility finding by the jury as to the reasons why she was in the car with Mr. Marshall that evening. But “it is not the function of this Court to reweigh conflicting evidence or consider the credibility of witnesses.” United States v. Pearson, 798 F.2d 385, 387 (10th Cir.1986) (citing United States v. Petersen, 611 F.2d 1313, 1317 (10th Cir. 1979), cert. denied, 447 U.S. 905, 100 S.Ct. 2985, 2986, 64 L.Ed.2d 854 (1980)). By viewing the evidence in the light most favorable to the government, we necessarily resolve any conflicts in the evidence in favor of the government and we assume the trier of fact found that evidence credible. Because we find sufficient evidence to support Ms. Parker’s conviction for aiding and abetting Mr. Marshall in distributing crack cocaine as charged in count six. We now consider Ms. Parker’s challenge to the sufficiency of the evidence with respect to her conspiracy conviction. b. Ms. Parker next challenges the evidence to support her conviction for conspiracy. She asserts the evidence failed to prove she knowingly entered into the conspiracy or that she agreed to achieve the ends of the conspiracy. Because a reasonable finder of fact could reach the opposite conclusion, we will not disturb the verdict. To establish the offense of conspiracy under 21 U.S.C. § 846, the government must prove, beyond a reasonable doubt, “that two or more persons agreed to violate the law, that the defendant knew at least the essential objectives of the conspiracy, that the defendant knowingly and voluntarily became a part of it, and that the alleged cocon-spirators were interdependent.” United States v. Angulo-Lopez, 7 F.3d 1506, 1510 (10th Cir.1993), cert. denied, - U.S.-, 114 S.Ct. 1563, 128 L.Ed.2d 209 (1994); accord United States v. Riggins, 15 F.3d 992, 994 (10th Cir.1994); United States v. Coleman, 7 F.3d 1500, 1502-03 (10th Cir.1993); United States v. Anderson, 981 F.2d 1560, 1563 (10th Cir.1992); United States v. Evans, 970 F.2d 663, 668 (10th Cir.1992), cert. de nied, - U.S. -, 113 S.Ct. 1288, 122 L.Ed.2d 680 (1993). To establish the first element of a conspiracy&emdash;that the defendant agreed to violate the law&emdash;the government’s evidence must show “ ‘a unity of purpose or a common design and understanding’ with coconspira-tors to accomplish one or more of the objects of the conspiracy.” Angulo-Lopez, 7 F.3d at 1510 (quoting United States v. Kendall, 766 F.2d 1426, 1431 (10th Cir.1985), cert. denied, 474 U.S. 1081, 106 S.Ct. 848, 88 L.Ed.2d 889 (1986)). The third element of a conspiracy&emdash; knowingly and voluntarily joining the conspiracy&emdash;must simply be supported by evidence that would permit the finder of fact to infer the requisite mens rea on the part of the defendant, that being a conscious and voluntary decision to join in the criminal venture. See United States v. Falcone, 311 U.S. 205, 210, 61 S.Ct. 204, 207, 85 L.Ed. 128 (1940) (“Those having no knowledge of the conspiracy are not conspirators.”). The evidence at trial demonstrated that Ms. Parker acted as a runner, delivering drugs to buyers and other members of the conspiracy for distribution purposes. As discussed above, there was testimony she aided and abetted a particular sale of crack to an undercover officer. Furthermore, there was testimony Ms. Parker served as a cook, who processed powder cocaine into crack. In exchange for these services, Mr. Marshall provided financial support to Ms. Parker, which included moving her into a house that Mr. Dryden had helped Mr. Marshall purchase. When this evidence is taken in its totality and in the light most favorable to the government, it is, in our view, legally sufficient to show Ms. Parker agreed to achieve the ends of the conspiracy and supports the inference that Ms. Parker consciously joined this criminal enterprise. 2. Mr. Dryden next asserts the district court committed reversible error in admitting, under Fed.R.Evid. 801(d)(2)(E), two tape recorded conversations between Ms. Williamson and Mr. Myles as substantive evidence bearing on his guilt relative to the conspiracy charge. Specifically, he asserts this evidence was improperly admitted for three reasons: (1) Mr. Myles was not a member of the conspiracy; (2) the statements were not made “during the course of’ the conspiracy; and (3) the statements were not made “in furtherance of’ the conspiracy. While we agree Mr. Myles was not a member of the conspiracy, we conclude, for reasons set forth below, that this error was harmless. Moreover, because we conclude the district court’s other preliminary findings under Rule 801(d)(2)(E) were correct, we find no error in the admission of these statements. District courts have broad discretion to admit or exclude evidence, and thus, appellate review of evidentiary rulings is limited only to determining whether, in light of the entire .record, the district court abused its discretion. See United States v. Jones, 44 F.3d 860, 873 (10th Cir.1995) (citing United States v. Zimmerman, 943 F.2d 1204, 1211 (10th Cir.1991) and Boren v. Sable, 887 F.2d 1032, 1034 (10th Cir.1989)). In addition, heightened deference to the trial judge is appropriate when we review rulings on matters involving the admission or exclusion of hearsay evidence. See Jones, 44 F.3d at 873 (citing Boren, 887 F.2d at 1033). Of course, while the ultimate issue of the admission or exclusion of evidence is reviewed for an abuse of discretion, preliminary foundational determinations, such as whether statements offered under Rule 801(d)(2)(E) were made “during the course of’ and “in furtherance of’ a conspiracy, are factual findings, reviewed for clear error. See Roberts, 14 F.3d at 514 (citing Smith, 833 F.2d at 221-22) (discussing Bourjaily v. United States, 483 U.S. 171, 107 S.Ct. 2775, 97 L.Ed.2d 144 (1987)). Fed.R.Evid. 801(d)(2)(E) provides: “a statement by a coconspirator of a party during the course and in furtherance of the conspiracy” is not hearsay, and is therefore admissible as substantive evidence against all other members of the conspiracy. In order for statements to be admissible under'Rule 801(d)(2)(E), the proponent of the evidence must establish, by a preponderance of the evidence, see Bourjaily, 483 U.S. at 176, 107 S.Ct. at 2779; Smith, 833 F.2d at 221, that: (1) a conspiracy existed; (2) the declarant and the defendant were both members of the conspiracy; and (3) the statements were made during the course of, and in furtherance of, the conspiracy. See Johnson, 4 F.3d at 914 (citing cases). In the present case, the district court exercised its discretion and elected not to conduct a James hearing prior to trial to determine the admissibility of any coconspirator statements the government would be introducing at trial pursuant to Rule 801(d)(2)(E). See Roberts, 14 F.3d at 514 (acknowledging “we have never constructed a fixed formula to govern the James prophylaxis.”); see also Petersen, 611 F.2d at 1329. During the course of the trial, the government sought to introduce two tapé recorded conversations between Ms. Williamson, an alleged cocon-spirator, and Mr. Myles, an undercover informant working for the prosecution. The first conversation took place on October 10, 1990, and the second occurred on January 18,1991. Over objection, the district court admitted these conversations as substantive evidence bearing on the guilt of all defendants, including Mr. Dryden, pursuant to Rule 801(d)(2)(E). See United States v. Wolf, 839 F.2d 1387, 1394 (10th Cir.) (“[Statements made by one eoconspirator in furtherance of the conspiracy are attributed to each member of the conspiracy”), cert. denied, 488 U.S. 923, 109 S.Ct. 304, 102 L.Ed.2d 323 (1988). In so doing, the court made the factual determinations that both Mr. Myles and Ms. Williamson were members of the conspiracy, and that the statements were made during the course of, and in furtherance of, the conspiracy. a. The government’s evidence as to Mr. Myles demonstrated that prior to May 3, 1988, he had been a drug dealer who purchased part of his supply of drugs from Mr. Marshall. In his own words, Mr. Myles stated, in reference to Mr. Marshall, “I didn’t work for him, but I bought from him. I did my own distributing.” He characterized Mr. Marshall as one of several suppliers from whom he would buy his drugs, which he would then re-sell to his own buyers in the hopes of “doubl[ing] [his] money.” He also indicated he “never dealt for anybody,” emphasizing he was an independent drug dealer who set his own prices, made his own profits and whose relationship with Mr. Marshall was that of buyer-seller, not employer-employee. The lack of any evidence showing that Mr. Myles received any form of compensation from Mr. Marshall for his services further corroborates Mr. Myles’ testimony that he did not work for Mr. Marshall. On May 3, 1988, Mr. Myles sold an ounce of crack cocaine to an undercover officer. He had previously sold that same officer a half ounce of crack cocaine on an earlier occasion. Shortly thereafter, Mr. Myles was arrested, at which time it appears he agreed to what can be characterized as an informal arrangement with the Kansas City police force. Although the record is not entirely clear, it appears that in exchange for Mr. Myles’ agreement to provide the police with information regarding Mr. Marshall and his operations, the prosecution would consider not bringing charges against Mr. Myles. Some time in 1991, Mr. Myles was asked to cooperate with the federal government regarding Mr. Marshall's operations, and he acceded to this request as well. Based on this evidence, the district court concluded the conversations were admissible under Rule 801(d)(2)(E). It is settled law in this circuit that “‘[p]roof of the existence of a buyer-seller relationship, without more, is inadequate to tie the buyer to a larger conspiracy.’ ” United States v. Fox, 902 F.2d 1508, 1514 (10th Cir.) (quoting United States v. McIntyre, 836 F.2d 467, 471 (10th Cir.1987)), cert. denied, 498 U.S. 874, 111 S.Ct. 199, 112 L.Ed.2d 161 (1990). “Mere association with conspirators, even with knowledge of their involvement in crime, is insufficient to prove participation in their conspiracy.” Fox, 902 F.2d at 1514; accord Jones, 44 F.3d at 866 (citing cases). In the absence of some evidence demonstrating that Mr. Myles knowingly and voluntarily joined the conspiracy and accepted the conspiratorial objectives, he cannot be transformed into a eoconspirator merely because he bought drugs from a known member of a drug conspiracy. Because the record is devoid of any evidence tending to support an inference that Mr. Myles was a member of Mr. Marshall’s drug conspiracy, it necessarily follows that the district court’s finding that Mr. Myles was a eoconspirator was clearly erroneous. Although the district court erred in finding Mr. Myles was a member of the conspiracy, this error does not automatically warrant reversal in this case. In fact, a review of Rule 801(d)(2)(E) and the case law interpreting it, demonstrates that the rule does not embody a requirement that the statement in question “be made by a cocon-spirator to a coconspirator.” United States v. Thompson, 976 F.2d 666, 670 (11th Cir. 1992) (emphasis added), cert. denied, — U.S. -, 113 S.Ct. 3010, 125 L.Ed.2d 701 (1993). Perhaps conspicuous by its absence is any requirement under Rule 801(d)(2)(E) that before coconspirator statements may be admitted, the party to whom the statements were made (i.e., the witness who will testify in court as to the out-of-court statements made by the declarant) must be a member of the conspiracy. Rule 801(d)(2)(E) only requires that the declarant (i.e., Ms. Williamson) and the defendant (i.e., the coconspirator on trial against whom the statement is being offered, who, in this case, is Mr. Dryden) be members of the conspiracy. Relying on this principle, the government asserts it is irrelevant whether the party to whom the statements are made (i.e., Mr. Myles) is a coconspirator as long as the declarant and the defendant are coconspirators. In support of this proposition, the government relies heavily on United States v. Mealy, 851 F.2d 890 (7th Cir.1988). In Mealy, the Seventh Circuit held “the fact that one party to a conversation [is] a government informant does not preclude the admission of the conspirator’s statements under Rule 801(d)(2)(E).” Mealy, 851 F.2d at 901 (emphasis added). We emphasize the italicized language to highlight the fact that the statements of the witness (the person to whom the out-of-court statements were made) are not admissible under this rule, but only the statements of the declarant/coeon-spirator that were made to the witness. The Seventh Circuit has continued to adhere to this holding of Mealy in subsequent decisions. See United States v. Mahkimetas, 991 F.2d 379, 383 (7th Cir.1993); United States v. Robinson, 956 F.2d 1388, 1394 (7th Cir.), cert. denied, — U.S.-, 113 S.Ct. 654, 121 L.Ed.2d 581 (1992); see also United States v. Messino, 855 F.Supp. 973, 977 (N.D.Ill.1994) (following Mealy). We agree with the reasoning and the analysis articulated by the Seventh Circuit in Mealy and its progeny, and we now explicitly hold “that the fact that one party to a conversation is a government agent or informer does not of itself preclude the admission of statements by the other party — if he or she is a member of a conspiracy — under Rule 801(d)(2)(E).” Mahkimetas, 991 F.2d at 383 (citations omitted). Stated alternatively, in deciding whether statements are admissible under Rule 801(d)(2)(E), the appropriate focus is on whether the statements were “made by” a member of the conspiracy, and not on whether the statements were “made to” a member of the conspiracy. Applying these principles to this ease, we conclude that although the district court erred in finding that Mr. Myles was a cocon-spirator, that error was harmless because it in no way affects the admissibility of these statements under Rule 801(d)(2)(E) because whether Mr. Myles was a eoconspirator is irrelevant. A fortiori, this error could not, and did not, have a substantial influence on the outcome of the trial. See Jones, 44 F.3d at 873. This conclusion flows from the undisputed facts that the declarant of the statements, Ms. Williamson, and the defendant against whom the statements are offered, Mr. Dryden, were both members of the conspiracy. Under Rule 801(d)(2)(E), this is sufficient to establish this aspect of the foundational requirement for the admission of this evidence. We must now determine whether the remaining foundational requirements—that the statements have been made during the course of and in furtherance of the conspiracy—have been satisfied as well. b. We summarily reject Mr. Dryden’s argument that these statements were not made “during the course of’ the conspiracy. He contends that in May of 1988, when Mr. Myles was arrested and agreed to become an informant, Mr. Myles’ participation in the conspiracy, if any, terminated and therefore, any statements he made were not made “during the course of’ the conspiracy. This argument is misdirected, however, because it wrongly focuses on Mr. Myles, rather than the declarant, Ms. Williamson. It is Ms. Williamson’s statements that the government contends were properly admissible under Rule 801(d)(2)(E), and not Mr. Myles’ statements. In fact, the preceding discussion makes it abundantly clear that Mr. Myles’ statements are not admissible under Rule 801(d)(2)(E). Once the proper focus of this inquiry is defined, it cannot reasonably be disputed that Ms. Williamson’s statements, which were made in October of 1990 and January of 1991, were well within the time frame of the conspiracy at issue. Therefore, we agree with the district court’s finding that this foundational requirement was satisfied. c. The final argument advanced by Mr. Dryden on this issue is that the statements in question were not made “in furtherance of’ the conspiracy. In essence, the statements by Ms. Williamson to Mr. Myles, which were offered as evidence against Mr. Dryden, fall neatly into four categories. The statements relate to: (1) identifying the names and roles of other members of the conspiracy; (2) avoiding detection by law enforcement personnel; (3) allaying the concerns and fears of Mr. Myles in order to maintain his confidence and trust; and (4) inducing the continued participation of Mr. Myles. We address, and ultimately reject, Mr. Dryden’s arguments that these statements were not “in furtherance of’ the conspiracy. First, statements identifying members of a conspiracy are statements “in furtherance of’ a conspiracy, see United States v. Caro, 965 F.2d 1548, 1557 (10th Cir.1992), as are statements discussing the particular roles of other coconspirators. See United States v. Magee, 821 F.2d 234, 244 (5th Cir. 1987) (“Ordinarily, a statement that identifies the role of one co-conspirator to another is in furtherance of the conspiracy.”); see also United States v. Lechuga, 888 F.2d 1472, 1480 (5th Cir.1989) (statement identifying co-conspirator as the source of the supply of drugs is a statement “in furtherance of’ the conspiracy). Second, statements by Ms. Williamson identifying Mr. Dryden as a member of the conspiracy, and describing his function in assisting the organization in avoiding detection by law enforcement, are also “in furtherance of’ the conspiracy for reasons stated in the preceding paragraph. They are statements of identity and of a particular individual’s role in the conspiracy. Furthermore, “conspiracies, by definition, are formed to commit criminal acts_ Avoiding detection by law enforcement officials clearly furthers the aims of a conspiracy.” United States v. Troop, 890 F.2d 1393, 1404 (7th Cir.1989). Third, our decision in Perez recognizes that statements by a coeonspirator designed to allay the fears and suspicions of another individual are statements “in furtherance of’ the conspiracy. See United States v. Perez, 989 F.2d 1574, 1578 (10th Cir.1993). The transcripts of the recorded conversations demonstrate Mr. Myles expressed concerns over Mr. Dryden’s trustworthiness, at which time Ms. Williamson explained to him why his concerns were unfounded. These statements clearly fall within the ambit 'of Rule 801(d)(2)(E). Fourth, Perez also supports the district court’s finding that Ms. Williamson’s statements attempting to induce Mr. Myles’ future involvement with Mr. Marshall were statements made “in furtherance of’ the conspiracy. See Perez, 989 F.2d at 1578. Accordingly, we conclude the district court’s factual findings that these statements were “in furtherance of’ the conspiracy are amply supported by the record. Finally, Mr. Dryden makes vague references to the unfair prejudice resulting from the admission of these statements. Even construing this argument as a claim under Fed.R.Evid. 403, we are not persuaded Mr. Dryden has carried his burden of demonstrating that he suffered any “unfair” prejudice from the admission of these statements, see United States v. Flanagan, 34 F.3d 949, 953 (10th Cir.1994), especially given the probative value for which these statements were introduced. Therefore, we find no abuse of discretion under Rule 403 in the admission of these statements. Id. 3. Ms. Williamson next asserts the prosecutor improperly cross-examined her by asking her questions that required her to testify that several of the prosecution’s witnesses who testified were lying. Because no objection was raised to this line of cross-examination by trial counsel, our review is limited to determining whether this examination constituted plain error. See United States v. Olano, — U.S. -, -, 113 S.Ct. 1770, 1778, 123 L.Ed.2d 508 (1993) (discussing Fed.R.Crim.P. 52(b)). “‘To constitute plain error, the district court’s error must have been both “obvious and substantial.”’” Barber, 39 F.3d at 288 (quoting United States v. Brown, 996 F.2d 1049, 1053 (10th Cir.1993)). The substantiality requirement of the plain error rule embodies a requirement that the defendant prove prejudice attributable to the error. See Olano, — U.S. at-, 113 S.Ct. at 1778. In support of her claim of prosecutorial misconduct, Ms. Williamson relies exclusively on a line of eases from the Second Circuit, beginning with the decision in United States v. Richter, 826 F.2d 206 (2d Cir.1987). Because the principle enunciated in Richter is an issue of first impression in this circuit, we begin our analysis with a discussion of Richter and its progeny. In Richter, the Second Circuit stated “[d]e-terminations of credibility are for the jury ... not for witnesses ... [and therefore] [p]rosecutorial cross-examination which compels a defendant to state that law enforcement officers lied in their testimony is improper.” Richter, 826 F.2d at 208 (citations omitted). The court admonished prosecutors “to avoid statements to the effect that, if the defendant is innocent, government agents must be lying.” Id at 209 (citations omitted). The facts in Richter demonstrated that during cross-examination of the defendant, the prosecutor asked several questions designed to make Mr. Richter to testify that an FBI agent was either mistaken or lying. Id. at 208. The court indicated that if the basis for claiming reversible error was only the questions asked of the defendant on cross-examination, the court “might be inclined to overlook the impropriety.” Id. But because the prosecutor went further in harping on this issue before the jury, the sum total of the prosecutor’s actions was deemed to be sufficiently egregious to constitute plain error warranting a new trial. Id. at 208-10. The additional conduct by the prosecutor besides the cross-examination of the defendant involved calling another FBI agent as a rebuttal witness “for the purpose of corroborating [the first agent’s] testimony, which the prosecutor already had forced the defendant to label as false,” id. at 208; and highlighting the discrepancies between the defendant’s statements to the agents and the defendant’s own testimony during closing argument, including a statement that the jury could determine Mr. Richter was not telling the truth ‘“because if he is, then these two agents, over and over again, committed perjury.’” Id. at 209. The Second Circuit has revisited Richter on five separate occasions. In United States v. Durrani, 835 F.2d 410 (2d Cir.1987), the court emphasized that reversal in Richter was warranted because of a combination of facts, including the questions asked on cross-examination and the statements made during closing argument. Id. at 424. In United States v. Kiszewski, 877 F.2d 210 (2d Cir.1989), the court distinguished Richter by noting that reversal was required in that case because of the cumulative effect of the cross-examination, the calling of a rebuttal witness and the emphasis on the discrepancies that were highlighted during closing argument. Id. at 217. The court also indicated that the issue in Richter did not turn on the veracity of the FBI agents, whereas in this case, a prosecution for making false declarations, “truthfulness was the central issue.” Id. In United States v. Scanio, 900 F.2d 485 (2d Cir.1990), the court again distinguished Richter on its facts. While acknowledging the rule in Richter was “not limited to situations where the defendant is asked to comment on the testimony of government agents,” id. at 493 (emphasis added), the court believed this fact raised “special con-cernís]” because of the “heightened credibility of government agents,” id