Full opinion text
WOLLMAN, Circuit Judge. A federal jury found Angela Johnson guilty of aiding and abetting the murder of five individuals while working in furtherance of a continuing criminal enterprise (CCE), violations of 21 U.S.C. § 848(e)(1)(A) and 18 U.S.C. § 2, and five counts of aiding and abetting the killing of these individuals while engaging in a drug conspiracy, also in violation of 21 U.S.C. § 848(e)(1)(A) and 18 U.S.C. § 2. The jury voted to impose the death penalty for four of these murders and voted to impose a sentence of life in prison for the fifth murder, resulting in a total of eight death sentences and two life sentences. Following her convictions, Johnson filed a motion in arrest of judgment, a motion for acquittal, and a motion for a new trial — all of which were denied by the district court in a comprehensive memorandum opinion. See United States v. Johnson, 403 F.Supp.2d 721 (N.D.Iowa 2005). Johnson appeals from her convictions and her sentences, raising 28 issues. We remand the ease so that the district court may vacate five of her ten convictions. In all other respects, we affirm. I. As set forth in greater detail below, this case revolves around five murders. In July of 1993, Johnson’s boyfriend, Dustin Honken, with Johnson’s help, abducted and killed Greg Nicholson, Lori Duncan (Nicholson’s girlfriend), and Duncan’s two young daughters, Amber and Kandi. Nicholson, who had sold drugs for Honken, was the central witness in a drug case against Honken. The Duncans had the misfortune of being present when Honken and Johnson arrived at their home to deal with Nicholson. Months later, Honken, again with Johnson’s assistance, murdered a second potential witness against Honken, Johnson’s former boyfriend, Terry De-Geus. In 1992, Honken started manufacturing methamphetamine with his friend Tim Cutkomp in Arizona. Honken’s brother, Jeff Honken, financed the operation. Honken distributed the methamphetamine to Greg Nicholson and Terry DeGeus, who were both drug dealers in Mason City, Iowa. In early 1993, during one of Honk-en’s trips to Mason City, DeGeus sent Johnson, who was his girlfriend at the time, to deliver either drug proceeds or methamphetamine to Honken. Johnson told Honken that because DeGeus was using too much of the methamphetamine for his own personal use, Honken should deal directly with Johnson instead. Johnson and Honken began a romantic relationship and within six months, Johnson became pregnant with Honken’s child. In late February or early March of 1993, Cut-komp moved to Iowa, but continued participating in Honken’s drug enterprise. In March 1993, police began investigating Nicholson and executed a search warrant for his residence, which led to the discovery of a large amount of methamphetamine and money. Nicholson agreed to cooperate with law enforcement and told agents that Honken had supplied him with several pounds of methamphetamine over a period of 10-11 months, for which he paid Honken a total of approximately $100,000. On March 21, 1993, Nicholson met with Honken to deliver drug proceeds. During their conversation, which was monitored by police, they discussed past and future deliveries of methamphetamine. That day, police arrested Honken and Cut-komp. In Honken’s pocket, officers found a note listing money owed to Honken by two individuals referred to as “G-man” and “T-man.” A receipt for the purchase of chemicals was found in Cutkomp’s pocket. After Honken was arrested, Jeff Honken disposed of items from Honken’s drug lab that Honken had kept in one of Jeff Honk-en’s storage sheds. In April 1993, a federal grand jury indicted Honken for conspiracy to distribute methamphetamine. Honken was released on bond. Honken informed the court that he intended to plead guilty, and a plea hearing was scheduled for July 30, 1993. During June and July of 1993, Honken and Johnson began searching for Nicholson. On the evenings they looked for Nicholson, Johnson would ask her friend, Christi Gau-batz, to babysit Johnson’s daughter. Honken and Johnson borrowed Gaubatz’s car on these occasions so that they would not be spotted by Nicholson. On July 7, 1993, Johnson purchased a semi-automatic 9 mm assault pistol at a pawn shop about an hour’s drive from her home. The last time Johnson asked Gaubatz to babysit so that she and Honken could look for Nicholson was July 24, 1993. That evening, Nicholson, Nicholson’s girlfriend, Lori Duncan, and Lori Duncan’s two children, Kandi and Amber, were murdered. Johnson later recounted the details of the murders to various witnesses. The following recitation is drawn from these accounts. Johnson knocked on the door of the Duncans’ home and asked if she could look at their telephone book. Johnson was carrying a cosmetics demonstration bag and claimed that she had an appointment to give a demonstration, but was uncertain of the address. She secured entry into the house, with Honken apparently right behind her. There was testimony that once the door was opened, Honken and Johnson “rushed” the occupants. While Johnson and Honken were in the house, one or both of them videotaped Nicholson making statements exculpating Honken. At some point, Johnson went upstairs with Kandi and Amber and had them pack up some of their things — either to persuade the girls that they were going on a trip or to convince any subsequent visitors to the house that they had done so. Honken and Johnson bound and gagged the adults with materials that either Honken or Johnson had brought to the house and drove the victims to a wooded area. Honken took the two adults out of the car and shot them in the head while Johnson waited in the car with the children. The children were then taken out of the car and shot as well. All four were placed in a single grave that had been dug earlier. As set forth below, their bodies were eventually discovered years later. After the murders, Honken provided his attorney with the videotape in which Nicholson exculpated Honken. When Honk-en appeared for his plea hearing, which took place five days after the murders, he declined to plead guilty. His attorney told the prosecutor that the case was not as strong as the government had believed. The tape was eventually returned to Honk-en and never seen again. With Nicholson missing, the government’s attention turned to DeGeus. On October 27, 1993, several individuals were subpoenaed, including Johnson and De-Geus’s friend, Aaron Ryerson. Ryerson was questioned about possible connections between Honken and DeGeus. After Ryerson spoke with DeGeus, DeGeus called Johnson and told her what Ryerson had said to him about his time before the grand jury. Nine days later, on November 5, DeGeus dropped his daughter off at his parents’ house and told them that he was going to meet with Johnson. By this time, DeGeus suspected that something may have happened to Nicholson, and he was concerned that he might share Nicholson’s fate. Although DeGeus knew that Johnson was involved with Honken, he apparently agreed to meet with her because he still had strong feelings for her. DeGeus was murdered that night. The evidence indicates that DeGeus was either shot by Honken and then beaten with a baseball bat or beaten first and then shot. Following DeGeus’s disappearance, Johnson gave conflicting reports to police and others about the night he disappeared, telling some individuals that she had not seen him that night and telling others that she had seen him, but that he had left after they had spoken. During the fall of 1993, Gaubatz found a bag containing a large black handgun, which had a silencer attached to it, in her closet. Upset by this discovery, Gaubatz called Johnson, who retrieved the weapon. In March 1995, the federal drug charges against Honken were dismissed. In 1995, Honken enlisted the assistance of Dan Co-been to help with the methamphetamine operation, but before Cobeen was allowed to participate, Honken took him to see Johnson for her approval. Unbeknownst to Honken or Johnson, however, Cobeen was cooperating with law enforcement and provided the authorities with information about the methamphetamine operation. On February 7, 1996, before Honken and his associates were able to produce methamphetamine, law enforcement agents executed a search warrant for Honken’s home, whereupon they seized items related to the production of methamphetamine. Two months later, the government brought drug charges against Honk-en and Cutkomp. After Honken’s arrest, Honken and Johnson discussed killing witnesses, including Cobeen and law enforcement agents. Cutkomp testified that Honken was reluctant to involve Johnson in any efforts to kill Cobeen because she was a “hot head and just wanted to go do—just do it.” Cutkomp was also worried about Johnson pushing Honken to follow through with the plans. Honken pled guilty to drug charges in 1997. Around the time of the sentencing hearing, Johnson called Jeff Honken and yelled, “[I]f Dustin wasn’t going to be able to see his kids she was going to make sure [Jeff Honken wasn’t] going to be able to see [his].” Johnson was charged with the murders in July 2000 and taken to the Benton County, Iowa, Jail, where she met another inmate, Robert McNeese. McNeese convinced Johnson that he was connected to the mob and that he could find an inmate already serving a life sentence who would confess to the murders. He told her that all he needed was information about the crimes so that this inmate could convince the authorities of his involvement. Johnson obliged, providing maps depicting the location of the victims’ bodies and information about how they were killed. McNeese then provided this information to the authorities. Using the maps, officers found Nicholson and the Duncan family in a single grave. The two adults were found bound and gagged and had been shot multiple times, suffering gunshots to the head. DeGeus’s body was found a few miles away in a field behind an abandoned house. He had suffered multiple gunshot wounds, and his skull had been fractured into dozens of pieces. Johnson’s trial was trifurcated into three phases: a “merits” phase, in which the jury found her guilty of the murders, an “eligibility phase,” in which the jury determined that she was eligible for the death penalty, and a “selection phase,” in which the jury voted for the death penalty for Johnson’s participation in the deaths of Lori Duncan, Amber Duncan, Kandi Duncan, and Terry DeGeus. The jury voted for life imprisonment for Johnson’s participation in Greg Nicholson’s murder. In a separate trial, Honken was also convicted of the murders, but Honken, unlike Johnson, received life sentences for the murders of Lori Duncan and DeGeus. II. As indicated earlier, Johnson raises 28 issues on appeal. We will discuss in detail only those issues that we believe merit extended treatment, addressing the issues in roughly the same order as Johnson has presented them. 1. The proportionality of Johnson’s death sentences under the Eighth Amendment Johnson argues first that the district court erred in denying her motion to strike the death penalty from the indictment. She contends that because Honken, the principal, received life sentences for the murders of DeGeus and Lori Duncan, imposing the death penalty for their murders upon Johnson, who had only aided and abetted the killings, would be a disproportionate punishment, in violation of the Eighth Amendment. She also contends that because she was a mere aider and abettor whose conduct did not lead to the deaths of the victims, she was ineligible for the death penalty for any of the murders. Johnson provides little support for her contention that a district court may strike the death penalty from the indictment despite the government’s compliance with the statutory prerequisites for seeking the death penalty. Nevertheless, because Johnson also appears to articulate a freestanding Eighth Amendment claim, we will address the merits of her contention that the imposition of the death penalty would constitute cruel and unusual punishment. We do not believe that the disparity between Honken’s and Johnson’s sentences violates the Eighth Amendment. While the Supreme Court has “occasionally struck down punishments as inherently disproportionate, and therefore cruel and unusual,” Pulley v. Harris, 465 U.S. 37, 43, 104 S.Ct. 871, 79 L.Ed.2d 29 (1984), the Court’s review has traditionally entailed “an abstract evaluation of the appropriateness of a sentence for a particular crime.” Id. at 42-43, 104 S.Ct. 871. In other words, traditional proportionality review hinges on whether a particular kind of crime warrants a particular punishment. For example, the Court has concluded that imposing the death penalty for the rape of an adult woman “is grossly disproportionate and excessive punishment for the crime of rape and is therefore forbidden by the Eighth Amendment as cruel and unusual punishment.” Coker v. Georgia, 433 U.S. 584, 592, 97 S.Ct. 2861, 53 L.Ed.2d 982 (1977). Similarly, the Court has determined that the death penalty is a disproportionate penalty for a defendant who is guilty of felony murder, but who did not kill, attempt to kill, or intend or contemplate that a killing would occur. Enmund v. Florida, 458 U.S. 782, 801, 102 S.Ct. 3368, 73 L.Ed.2d 1140 (1982). Johnson contends that the Eighth Amendment requires not only proportionality between a sentence and a particular category of crime, but also proportionality between eodefendants’ sentences. We disagree. The Supreme Court has rejected similar contentions, noting in McCleskey v. Kemp, 481 U.S. 279, 306-07, 107 S.Ct. 1756, 95 L.Ed.2d 262 (1987), that a defendant cannot “prove a constitutional violation by demonstrating that other defendants who may be similarly situated did not receive the death penalty.” Id.; see also United States v. Chauncey, 420 F.3d 864, 876 (8th Cir.2005) (remarking that “a defendant’s sentence is not disproportionate merely because it exceeds his codefen-dant’s sentence”), cert. denied, 547 U.S. 1009, 126 S.Ct. 1480, 164 L.Ed.2d 258 (2006). It bears mention, too, that although we assume that the government presented similar evidence in both Honk-en’s and Johnson’s trials, the evidence may have differed slightly. In particular, Johnson has not apprised us of the mitigation evidence Honken presented in his trial. Two juries hearing similar, but not identical, evidence may well reach different conclusions regarding the proper penalty for their respective defendants. In addition, different verdicts may permissibly reflect not only differences between the facts presented at trial, but differences between the juries themselves. “Individual jurors bring to their deliberations qualities of human nature and varieties of human experience, the range of which is unknown and perhaps unknowable.” McCleskey, 481 U.S. at 310-11, 107 S.Ct. 1756 (citation and quotation marks omitted). One cannot expect that two different juries—each of which is composed of citizens with diverse backgrounds and values—must necessarily reach the same verdict. Johnson contends that Enmund supports the proposition that courts “must evaluate a defendant’s culpability both individually and in terms of the sentences of codefendants and accomplices in the same case.” (Appellant’s Br. at 19). Johnson’s reliance on Enmund is misplaced. In En-mund, two people were murdered during the course of a robbery while Enmund was sitting nearby in a car, waiting to help the robbers escape. Enmund was not present during the murders, did not intend that the victims be killed, and had not anticipated that “lethal force would or might be used if necessary to effectuate the robbery or a safe escape.” Enmund, 458 U.S. at 788, 102 S.Ct. 3368. Both Enmund and the codefendants who had actually committed the murders were sentenced to death. The Supreme Court concluded that a death sentence “is an excessive penalty for the robber who, as such, does not take human life,” id. at 797, 102 S.Ct. 3368, and that the death penalty was a disproportionate penalty for Enmund because he did not “kill, attempt to kill, or intend that a killing take place or that lethal force will be employed.” Id. at 797, 102 S.Ct. 3368. Enmund thus holds that the death penalty is too harsh a penalty for a certain category of crime. In sum, we do not believe that Enmund assists Johnson, and we reject her contention that the disparity between her sentence and Honken’s violates the Eighth Amendment. See Hatch v. Oklahoma, 58 F.3d 1447, 1466-67 (10th Cir.1995) (holding that the Eighth Amendment does not require codefendants’ sentences to be proportional to one another). Johnson also argues that the death penalty was disproportionate under Enmund and Tison v. Arizona, 481 U.S. 137, 107 S.Ct. 1676, 95 L.Ed.2d 127 (1987), because she was only minimally involved in the murders, the deaths did not result from her actions, and she had not foreseen that life would be taken. We conclude that these contentions are unavailing. First, there was evidence that the killings resulted from her substantial participation in the murders; namely, that she procured the murder weapon, participated in the hunt for Nicholson, employed a ruse so that she and Honken could gain entry to the Duncans’ residence, bound and gagged at least one of the victims, and exploited her relationship with DeGeus to lure him to the remote location where he was killed. There was thus sufficient evidence that Johnson was an essential participant in the murders. There was also evidence that she intended that the killings occur. First, the jury reasonably rejected Johnson’s suggestion that she had, at most, intended to participate in kidnaping Nicholson and the Dun-cans. Nicholson was a potential witness; if he remained alive there would be a danger that he might recant the exculpatory remarks he made about Honken in the videotape. The Duncans were witnesses to Honken’s and Johnson’s treatment of Nicholson. To be efficacious for Honken’s and Johnson’s purposes, a kidnapping would have necessarily constituted an involved, long-term affair. There was no evidence that any such scheme was in the works. As for DeGeus’s murder, the jury could have concluded that Johnson lured DeGeus to a secluded location where Honken could kill him, particularly in light of the fact that Johnson knew that Honken had killed Nicholson and the Duncans months earlier. 2. Federal Rule of Criminal Procedure 24(b) and Equal Protection Johnson next argues that Federal Rule of Criminal Procedure 24(b) violates her equal protection rights. Under Fed. R.Crim.P. 24(b), defendants in non-capital felony cases are entitled to ten peremptory challenges, whereas the government receives six challenges. In a capital case, however, both the defendant and the government receive twenty peremptory challenges. Fed.R.Crim.P. 24(b)(1). Johnson argues that Rule 24(b) violates her equal protection rights because defendants in non-capital cases have a more favorable ratio of peremptory challenges vis-á-vis the government than do defendants in capital cases. Johnson’s argument is unavailing. We reject first Johnson’s suggestion that because Rule 24(b) burdens a fundamental constitutional right strict scrutiny applies. Peremptory challenges are not “of federal constitutional dimension.” United States v. Martinez-Salazar, 528 U.S. 304, 311, 120 S.Ct. 774, 145 L.Ed.2d 792 (2000). Instead, the right to peremptory challenges “is in the nature of a statutory privilege,” Frazier v. United States, 335 U.S. 497, 506 n. 11, 69 S.Ct. 201, 93 L.Ed. 187 (1948), provided to help secure the defendant’s constitutional right to a fair trial. Id. at 505, 69 S.Ct. 201. We also reject Johnson’s argument that Rule 24(b) fails rational-basis review. Johnson contends that if defendants need more peremptories than the government in non-capital cases, then defendants also need more peremptories than the government in capital cases. Rational-basis review, however, does not require a perfect or exact fit between the means used and the ends sought. Bankers Life & Cas. Co. v. Crenshaw, 486 U.S. 71, 85, 108 S.Ct. 1645, 100 L.Ed.2d 62 (1988) (noting that a statute need not be “perfectly calibrated in order to pass muster under the rational-basis test”). The legislature is not required to calculate with precision the exact number of challenges necessary to help secure the defendant’s right to a fair trial. Nor is the legislature required to arrive at a perfect defendant-to-government ratio. Although the government does not squarely proffer a reason for the disparity between the ratio of government-to-defendant challenges in capital and non-capital cases, its briefing suggests, and the progress of this case confirms, that in a capital case, the venire panel’s views on the death penalty become the primary pivot around which jury selection turns. The government and the defense arguably have an equal interest in exploring the jurors’ attitudes. Rule 24(b) may not be “perfectly calibrated,” perhaps, but it passes rational-basis muster. 3. Johnson’s Sixth Amendment rights and her right to peremptory challenges Johnson argues that her Sixth Amendment right to an impartial jury was violated because the district court erroneously denied her for-cause challenges to more than a dozen jurors. She also contends that the district court’s error impaired her right to exercise peremptory challenges because she was forced to expend a number of her peremptory challenges on jurors who should have been excused for cause. A. Sixth Amendment argument Because Johnson exercised peremptory challenges to prevent all the challenged jurors except juror 600 from sitting on her jury, juror 600 is the only juror about whom she can raise a Sixth Amendment objection. See United States v. Nelson, 347 F.3d 701, 710 (8th Cir.2003) (claim that district court erred by not excluding four penalty-phase jurors for cause lacked merit because the defendant had used peremptory challenges to prevent the challenged jurors from sitting on the jury); United States v. Paul, 217 F.3d 989, 1004 (8th Cir.2000) (noting that the defendant’s claim on appeal concerning district court’s denial of challenge for cause was unavailing because, inter alia, the three challenged jurors did not sit on the jury). The district court did not abuse its discretion in denying Johnson’s motion to strike juror 600. A venireperson may be properly excluded from sitting in a capital ease if the venireperson’s views on capital punishment would “prevent or substantially impair the performance of his duties as a juror in accordance with his instructions and his oath.” Wainwright v. Witt, 469 U.S. 412, 424, 105 S.Ct. 844, 83 L.Ed.2d 841 (1985). “Because the trial judge is in the best position to analyze the demeanor and credibility of a venireman, we will not reverse a court’s rulings absent an abuse of discretion.” United States v. Ortiz, 315 F.3d 873, 888 (8th Cir.2002); see also Uttecht v. Brown, — U.S. -, 127 S.Ct. 2218, 2223-25, 167 L.Ed.2d 1014 (2007) (concluding that a trial judge’s determinations regarding substantial impairment should be accorded deference). Johnson contends that juror 600 should have been struck because he stated that his empathy for the victim’s family and the fact that the crime involved children could affect his judgments about the case. She also asserts that juror 600 would not consider any deals that a prisoner may have received or might hope for in weighing the prisoner’s testimony. Although the juror gave some equivocal answers and acknowledged the possibility that his judgment could be affected by some aspects of the case, the district court concluded that juror 600 could be fair and impartial and that his statements reflected the “reasonable self doubts” of a conscientious and reflective person. Moreover, although he initially indicated little interest in whether witnesses hoped for sentencing reductions in exchange for their testimony, juror 600 stated that he would consider the motivations of witnesses in testifying and acknowledged the “real possibility” that some witnesses might lie to obtain some sort of benefit. We therefore cannot say that the district court abused its discretion in denying Johnson’s for-cause challenge to this juror. B. Impairment of her right to exercise peremptory challenges Johnson contends also that her statutory entitlement to twenty peremptory challenges was impaired because she was, as she puts it, forced to “waste” 60% of her peremptory challenges on jurors who should have been stricken for cause. We disagree. In Martinez-Salazar, the Supreme Court held that a defendant’s right to exercise peremptory challenges is not impaired when the defendant elects to use her challenges to remove jurors who should have been stricken for cause. Martinez-Salazar, 528 U.S. at 317, 120 S.Ct. 774. In reaching this conclusion, the Court noted that peremptory challenges are “auxiliary” to the right of an impartial jury and that they are one means of ensuring a fair trial, but are not themselves of “federal constitutional dimension.” Id. at 311, 120 S.Ct. 774; see also Frazier, 335 U.S. at 505, 69 S.Ct. 201 (“the right [to peremptory challenges] is given in aid of the party’s interest to secure a fair and impartial jury ... ”). Accordingly, Johnson did not, to use her phrase, “waste” her peremptory challenges. Instead, she “used the challenge[s] in line with a principal reason for peremptories: to help secure the constitutional guarantee of trial by an impartial jury.” Martinez-Salazar, 528 U.S. at 316, 120 S.Ct. 774. Johnson suggests that her case is distinguishable from Martinez-Salazar because unlike Martinez-Salazar, who “did not ask for a makeup peremptory or object to any juror who sat,” id. at 318, 120 S.Ct. 774 (Souter, J., concurring), Johnson requested additional peremptory challenges and objected to juror 600. She also asserts that her case is distinguishable, both from Martinez-Salazar, as well as cases applying Martinez-Salazar, because of the sheer number of challenges she expended in removing jurors that she thought should have been removed for cause. We do not consider this sufficient reason to depart from the Martinez-Salazar rule. The language used by the Court does not suggest that the rule of law Martinez-Salazar enunciates hinges on how many peremptory challenges the defendant exercised for curative purposes or how the defendant would have otherwise employed her challenges if she had not used them curatively. The constitutional touchstone, we believe, is the right to a fair trial, and we are not persuaded that Johnson has been deprived of this right. Nor has she shown that her jury or the voir dire process was constitutionally objectionable in any other way. Because Johnson received the twenty challenges to which she was entitled under Rule 24, and because she has not shown that she was denied either the right to a fair trial or any other constitutional right, we conclude that her claim is unavailing. 4. The denial of Johnson’s request for additional peremptory challenges The district court denied Johnson’s request for additional peremptory challenges beyond the twenty to which she was entitled under Rule 24. Johnson contends that the denial was improper because she needed the additional challenges to cure the effects of pretrial publicity. Assuming for the sake of argument that the district court had the authority to grant additional peremptory challenges, we cannot discern any error in the denial of Johnson’s motion. Johnson was able to challenge for cause jurors adversely affected by pretrial publicity and, if those challenges were denied, exercise her peremptory challenges. She does not appear to allege that any of the sitting jurors were prejudiced by pretrial publicity. Moreover, as the district court noted, the responses to the juror questionnaires indicated that the influence of pretrial publicity did not appear likely to impair Johnson’s ability to receive a fair trial. Johnson, 403 F.Supp.2d at 721, 768-69. If Johnson had felt that the voir dire testimony of the jurors belied that conclusion, she could have elected to renew her motion for a change of venue during, or at the conclusion of, jury selection, but she did not. Id. In light of the foregoing, we cannot say that the district court erred in declining to provide Johnson with a greater number of peremptory challenges than the 20 provided by Rule 24(b). 5. The district court’s exclusion of two jurors Johnson argues that the district court erred in striking for cause jurors 458 and 769. When juror 458 was asked if he would consider the death penalty an appropriate punishment for an intentional murder, he responded, “I'd have to say no,” adding, “I believe in mercy too.” Shortly thereafter he stated, “Well, I think living with the guilt is penalty enough in my opinion. You know, how much worse can it get?” He also remarked that he would vote for a life sentence without the possibility of parole 99% of the time. The district court’s determination that this juror was substantially impaired was not an abuse of discretion. Juror 769 gave markedly inconsistent and equivocal answers to the questions posed to her in the juror questionnaire and during voir dire, and twice expressed reservations about her ability to sign a verdict slip that would have the practical effect of sentencing someone to death. The district court remarked that juror 769 “was the quintessential example of a juror whose answers were so equivocal, ambiguous, and inconsistent, that the court was entitled, if not absolutely required, to remove her for cause.” Johnson, 403 F.Supp.2d at 784. We cannot say that excluding this juror constituted an abuse of discretion. 6. The prosecutor’s statements to the jurors that the jurors were permitted to give no weight to various mitigating factors Johnson contends that the district court erred in allowing the prosecutor to tell jurors during voir dire that, although they were required to consider them, the jurors were permitted to give certain mitigating evidence “no weight” in determining Johnson’s sentence. Johnson also asserts that the prosecutor improperly stated during the selection-phase closing arguments that the jurors should not give any weight to the fact that Johnson had no prior criminal record. Sentencers “may determine the weight to be given relevant mitigating evidence. But they may not give it no weight by excluding such evidence from their consideration.” Eddings v. Oklahoma, 455 U.S. 104, 114-15, 102 S.Ct. 869, 71 L.Ed.2d 1 (1982). A capital jury is not required “to give mitigating effect or weight to any particular evidence.” Paul, 217 F.3d at 999-1000 (citing Boyde v. California, 494 U.S. 370, 377, 110 S.Ct. 1190, 108 L.Ed.2d 316 (1990)). “There is only a constitutional violation if there exists a reasonable likelihood that the jurors believed themselves precluded from considering relevant mitigating evidence.” Id. at 1000 (citing Boyde, 494 U.S. at 386, 110 S.Ct. 1190). Based on our review of the voir dire transcript, particularly those portions of the transcript to which Johnson draws our attention, we conclude that the prosecutor’s comments and questions accurately reflected the law: jurors are obliged to consider relevant mitigating evidence, but are permitted to accord that evidence whatever weight they choose, including no weight at all. We also reject Johnson’s contention that the prosecutor improperly urged the jury to accord no weight to the fact that Johnson had no prior criminal record. The prosecutor did not suggest that the jury was permitted to exclude this factor from its consideration. Instead, the prosecutor acknowledged that Johnson had no prior criminal record, but suggested that this fact should be accorded no weight because there was evidence that Johnson had committed various crimes for which she had not been arrested or charged. 7. Sufficiency of the evidence Johnson argues that the evidence was insufficient to show that the murders were committed in furtherance of a conspiracy and that the government failed to establish the elements of CCE murder. A. Conspiracy Murder Johnson asserts first that the murders could not have been committed in furtherance of a drug conspiracy because the conspiracy had ended in late 1992 when Cutkomp left Arizona and Honken told his brother that he was going to stop producing methamphetamine. This assertion is incorrect because, despite what Honken may have told his brother, and despite Cutkomp’s move to Iowa, the evidence, including the evidence of the events culminating in Honken’s March 1993 arrest, demonstrates that Honken and Cut-komp had in fact continued their methamphetamine-related activities. Johnson also suggests that the conspiracy terminated no later than March 1993, when Honken and others were arrested and Nicholson began cooperating with the authorities. A conspiracy may persist, however, “even if the participants and their activities change over time, and even if many participants are unaware of, or uninvolved in, some of the transactions.” United States v. Roach, 164 F.3d 403, 412 (8th Cir.1998). Here, in addition to the murders undertaken to preserve the conspiracy, cf., United States v. Hamilton, 332 F.3d 1144, 1149-50 (8th Cir.2003) (“Eliminating a witness to a murder at the drug house could logically be seen to further the conspiracy by making it less likely that the operation would be shut down as a result of a murder investigation.”), there was sufficient evidence to support a finding that a conspiracy to manufacture and sell methamphetamine, with Honken at its center, continued from 1992 through 1996, Honken’s 1993 arrest notwithstanding. A couple of months after Honken was arrested, Honk-en asked Cutkomp to obtain chemicals so that Honken could produce more methamphetamine that Honken could sell to pay off Nicholson or DeGeus. Although Cut-komp did not complete that particular task, he testified that from the time of the disappearances through about 1995, he occasionally assisted Honken in Honken’s attempts to manufacture methamphetamine. Cutkomp’s participation also included trips to purchase chemicals in 1995 and the disposal of evidence in 1996. Johnson participated also. In addition to her role in the murders, in 1994, Johnson supplied money to purchase chemicals, and some of Honken’s attempts to manufacture methamphetamine took place at Johnson’s home. B. CCE Murder Johnson also argues that the government failed to prove the elements of CCE murder. To establish CCE murder, the government must prove: 1) that an individual is engaged in or working in the furtherance of a CCE; 2) that this person intentionally commanded, induced, procured or caused the killing; 3) that the killing actually resulted; and 4) that there was a substantive connection between the killing and the CCE. See United States v. Jones, 101 F.3d 1263, 1267 (8th Cir.1996). Here, Johnson was charged with aiding and abetting a CCE murder. Consequently, the district court instructed the jury that the second element of the offense would be met if Johnson aided and abetted the killing. The CCE alleged in this case was the drug operation organized by Honken. To establish the existence of this CCE, the government was required to prove: 1) that Honken committed a felony violation of the federal narcotics laws; 2) as part of a continuing series of three or more violations; 3) in concert with five or more other persons; 4) for whom Honken was an organizer, manager, or supervisor; 5) from which Honken derived substantial income or resources. See United States v. Jackson, 345 F.3d 638, 645 (8th Cir.2003) (citing United States v. Jelinek, 57 F.3d 655, 657 (8th Cir.1995)). Johnson alleges several infirmities in the government’s CCE murder case. She contends first that the CCE, like the conspiracy, had ended before the murders took place, reiterating the arguments she made regarding the conspiracy murder charge. For essentially the same reasons stated above, we conclude that this contention lacks merit. She also asserts that Honken did not supervise five or more CCE participants. In particular, she contends that two of the alleged CCE participants, Nicholson and DeGeus, were not managed by Honken because they had only a buyer-seller relationship with him. We disagree. The “management element is established by demonstrating that the defendant exerted some type of influence over another individual as exemplified by that individual’s compliance with the defendant’s directions, instructions, or terms.” United States v. Possick, 849 F.2d 332, 336 (8th Cir.1988). There was evidence that Nicholson and DeGeus were not merely customers, but were directed by Honken in a drug distribution scheme. They were often described as having sold drugs “for” Honken, and the evidence indicates that Honken “fronted” them the drugs, that they remitted some of their drug proceeds to Honken, and that this was an ongoing relationship coordinated by Honken. Cf. Possick, 849 F.2d at 336 (noting that although merely fronting drugs to another person will not suffice to establish supervision, supervision may be found where the defendant fronted another individual drugs and instructed him how to arrange for collection and payment of drugs); United States v. Apodaca, 843 F.2d 421, 427 (10th Cir.1988) (explaining that drug dealers who were fronted drugs by the defendant—to whom they passed back a portion of the proceeds from the drug sales—were not mere “consumers”). The quantity of drugs coupled with the ongoing relationship also suggests that Nicholson and DeGeus were not merely Honken’s customers. See United States v. Prieskorn, 658 F.2d 631, 634-35 (8th Cir.1981) (noting that the large quantity of cocaine and evidence of an ongoing relationship with suppliers indicated participation in conspiracy). We also note that Nicholson stored drugs for Honken. In sum, we conclude that Honken supervised Nicholson and DeGeus and that the elements of CCE murder were established. 8. Admission of evidence relating to Honken’s guilty plea Johnson moved in limine for the exclusion of evidence pertaining to Honk-en’s 1997 guilty plea, conviction, and sentence. Although she appears to agree that the fact of Honken’s 1997 conviction was relevant, she argued to the district court that neither Honken’s sentence nor the “particular crimes” with which Honken was charged and to which he pled guilty were relevant. The government responded that evidence of the specific charges was relevant to provide context for statements that Honken made to Cutkomp and Cobeen, but agreed that the sentence was not relevant. The district court ordered that evidence of the sentence be excluded, but ruled that evidence pertaining to the specific charges would be admitted. Accordingly, the government was permitted to introduce exhibits 303 and 304, which reflected the crimes with which Honken was charged, the sentences he received, and the amount of methamphetamine for which he was held accountable. The government was also allowed to introduce the transcript of Honken’s plea colloquy. During the merits-phase dosing arguments, one of the prosecutors stated, “There were two [violations] for which [Honken] pled guilty, Exhibits 303 and 304. In the evidence in this case—and you’ll have them back in the jury room— set forth his guilty plea and conviction as to two federal felony drug convictions.” Johnson contends that the two exhibits should not have been admitted and that the prosecutor improperly used this evidence of Honken’s guilty plea as substantive evidence of Johnson’s guilt. Cf. United States v. Rogers, 939 F.2d 591, 594 (8th Cir.1991) (per curiam) (“Any time a guilty plea of a co-offender is either directly or indirectly brought into a trial, trial courts must ensure that it is not being offered as substantive proof of the defendant’s guilt.”). We conclude that even if these exhibits were improperly admitted or used for an improper purpose, any error was harmless. Although Johnson argues that the jury should not have learned which specific crimes were involved, a reasonable juror who heard the other trial evidence would have assumed that the crimes in question involved methamphetamine. Similarly, the prospect of prejudice was diminished because, even without evidence of the guilty pleas, there was overwhelming evidence of Honken’s participation in methamphetamine-related crimes during the relevant period of time. Finally, Johnson’s defense did not center on whether or not Honken was involved in drug crimes, but rather on whether Johnson had knowingly participated in the murders. 9. Admission of bad acts evidence Johnson argues next that the district court erred in permitting the introduction of evidence pertaining to bad acts committed subsequent to the murders, some of which took place years after the killings. She asserts that these bad acts were either more prejudicial than probative under Federal Rule of Evidence 403 or constituted impermissible propensity evidence pursuant to Federal Rule of Evidence 404(b). We disagree. Johnson was charged with murders committed in furtherance of a methamphetamine conspiracy and a CCE that allegedly extended from 1992 through 1998. Most of the bad acts to which Johnson refers on appeal relate to Johnson’s participation in the production of methamphetamine or her attempts to influence witnesses to Honken’s methamphetamine offenses, which were relevant to establish the existence of, and Johnson’s involvement in, the conspiracy or CCE. Indeed, one of the subsequent bad acts about which Johnson complains, evidence that she possessed chemicals and equipment related to the manufacture of methamphetamine at her home in Clear Lake, Iowa, was one of the alleged predicate offenses. Johnson devotes most of her discussion of this issue to the admission of testimony by Rick Held, an acquaintance of Honk-en’s. Held testified that in 1998, a woman identifying herself as Honken’s girlfriend called him on the telephone and told him that Honken did not need a “pup” (which evidently referred to a firearm that Honk-en had asked Held to acquire for him) anymore. Johnson suggests that this testimony should not have been admitted because Honken had two girlfriends and thus the statement could not have been properly attributed to Johnson. There was evidence, however, from which the jury could infer that it was Johnson who made this call, rather than another girlfriend. Having examined the record, we conclude that admission of the other subsequent bad acts evidence was proper as well. 10. Admission of hearsay statements Johnson contends that the admission of certain hearsay statements violated both her confrontation rights as well as the Ex Post Facto Clause of the Constitution. Because most of the statements to which Johnson objects were made by Nicholson and DeGeus, we will devote most of our analysis to the admission of these statements. Nicholson’s and DeGeus’s hearsay statements were admitted pursuant to the forfeiture by wrongdoing doctrine as codified by Federal Rule of Evidence 804(b)(6). As we explained in United States v. Emery, 186 F.3d 921 (8th Cir.1999), a defendant’s confrontation rights under the Sixth Amendment are “forfeited with respect to any witness or potential witness whose absence a defendant wrongfully procures.” Id. at 926. “Hearsay objections are similarly forfeited under Fed. R.Evid. 804(b)(6), which excludes from the prohibition on hearsay any ‘statement offered against a party that has engaged or acquiesced in wrongdoing that was intended to, and did, procure the unavailability of the declarant as a witness.’ ” Id. (quoting Fed.R.Evid. 804(b)(6)). Forfeiture under Rule 804(b)(6) applies not only in the original cases for which the declarant was an actual or potential witness, but also in any prosecution pertaining to the wrongful procurement of the witness’s unavailability. Id. In Emery, for example, the defendant murdered the woman who was cooperating with law enforcement in a drug investigation against him. Id. at 924-26. We concluded that Emery had forfeited his hearsay and confrontation objections not only with respect to “a trial on the underlying crimes about which he feared [the victim] would testify,” but also “in a trial for murdering her.” Id. at 926. A. Ex Post Facto Clause Johnson argues that the Ex Post Facto Clause of the Constitution precludes the application of the forfeiture by wrongdoing doctrine in her case because the rule of evidence codifying the doctrine, Rule 804(b)(6), was enacted four years after the murders took place. The argument lacks merit because Rule 804(b)(6) reflects legal principles that were well and widely recognized at the time of the murders. See Fed.R.Evid. 804, notes of advisory committee on 1997 amendments (collecting cases). Moreover, even if the enactment of Rule 804(b)(6) had enlarged the category of admissible evidence in a criminal case, we doubt that this would constitute an ex post facto violation. The Ex Post Facto Clause prohibits, inter alia, the application of any “law that alters the legal rules of evidence, and receives less, or different testimony, than the law required at the time of the commission of the offense, in order to convict the offender.” Calder v. Bull, 3 U.S. 386, 390, 3 Dall. 386, 1 L.Ed. 648 (1798) (opinion of Chase, J.). Laws that “ ‘simply enlarge the class of persons who may be competent to testify in criminal cases’ do not offend the ex post facto prohibition because they do not ... alter the degree or lessen the amount or measure of proof necessary to convict the defendant.” Palmer v. Clarke, 408 F.3d 423, 430-31 (8th Cir.2005) (quoting Hopt v. Utah, 110 U.S. 574, 589, 4 S.Ct. 202, 28 L.Ed. 262 (1884)), cert. denied sub nom. Palmer v. Houston, 546 U.S. 1042, 126 S.Ct. 755, 163 L.Ed.2d 588 (2005). Accordingly, even if the enactment of Rule 804(b)(6) had enlarged the class of admissible hearsay, this expansion would not violate the Ex Post Facto Clause. We thus find unavailing Johnson’s ex post facto objection to Rule 804(b)(6). B. Applicability of the Forfeiture by Wrongdoing Doctrine Johnson also contends that her case is distinguishable from Emery and that the forfeiture by wrongdoing doctrine is inapplicable because she did not endeav- or to procure the unavailability of any witnesses against her. She also contends that the doctrine could not apply to her because she had been accused only of aiding and abetting the murders. The question, therefore, is whether the doctrine applies when a defendant aids and abets the murder of a potential witness against another person. We conclude that it does. We observe first that the scope of the forfeiture by wrongdoing doctrine under common law may differ from the version of the doctrine established by Rule 804(b)(6). The Sixth Circuit in United States v. Garcia-Meza, 403 F.3d 364 (6th Cir.2005), noted that although Rule 804(b)(6) may require that the defendant intend to procure a witness’s unavailability to testify, under the common law forfeiture doctrine a defendant’s confrontation rights may be extinguished even if her misconduct was not specifically directed toward rendering the witness unavailable. Id. at 370. Because the requirements for forfeiture under Rule 804(b)(6) are arguably more stringent than those under the common law version of the doctrine, a matter we need not and do not resolve today, and because the statements at issue here must, in any case, be admissible under the Federal Rules of Evidence (any forfeiture of Johnson’s confrontation rights notwithstanding), our analysis will focus on the requirements of the Rule 804(b)(6). The fact that Johnson may have only aided and abetted the procurement of the witnesses’ unavailability is of little moment, If a defendant’s role as an aider and abettor may constitute sufficient participation in a murder to warrant the imposition of a death sentence, such conduct should also suffice for the forfeiture of hearsay and confrontation objections. In other words, it “would make little sense to limit forfeiture of a defendant’s trial rights to a narrower set of facts than would be sufficient to sustain a conviction and corresponding loss of liberty.” United States v. Cherry, 217 F.3d 811, 818 (10th Cir.2000); see also United States v. Carson, 455 F.3d 336, 364 (D.C.Cir.2006) (suggesting that if members of a conspiracy agree to kill potential witnesses against them, all of the members of the conspiracy would be criminally responsible for resulting murders and “there is no good reason why the murder should give any of them an eviden-tiary advantage”), cert. denied, — U.S. -, 127 S.Ct. 1351, 167 L.Ed.2d 146 (2007). Furthermore, Rule 804(b)(6) applies when a defendant has “engaged or acquiesced in wrongdoing” procuring a witness’s unavailability. We believe that this language encompasses Johnson’s substantial involvement in procuring the witnesses’ unavailability. We also conclude that Rule 804(b)(6) applies to Johnson even though she had worked to procure the unavailability of potential witnesses against Honken rather than against herself. “ ‘Because the Federal Rules of Evidence are a legislative enactment, we turn to the traditional tools of statutory construction in order to construe their provisions. We begin with the language itself.’ ” United States v. Gray, 405 F.3d 227, 241 (4th Cir.2005) (quoting Beech Aircraft Corp. v. Rainey, 488 U.S. 153, 163, 109 S.Ct. 439, 102 L.Ed.2d 445 (1988)), cert. denied, 546 U.S. 912, 126 S.Ct. 275, 163 L.Ed.2d 245 (2005). The words of Rule 804(b)(6) provide only that the defendant must procure the unavailability of a witness—they do not specify the person against whom the unavailable witness was to have testified. After all, the purpose of Rule 804(b)(6), as the advisory committee to the Federal Rules of Evidence stated, was to enact a “prophylactic rule to deal with abhorrent behavior which strikes at the heart of the system of justice itself.” Fed.R.Evid. 804(b)(6), notes of advisory committee on 1997 amendments (citation and quotation marks omitted). Johnson’s conduct was no less abhorrent and no less offensive to “the heart of the system of justice itself’ because she procured the unavailability of witnesses against Honken rather than against herself. Moreover, applying Rule 804(b)(6) in Johnson’s case is consonant with the equitable rationales for the forfeiture by wrongdoing doctrine, which includes preventing individuals from profiting from their own wrongdoing. Gray, 405 F.3d at 242 (collecting cases and observing that “federal cases have recognized that the forfeiture-by-wrongdoing exception is necessary to prevent wrongdoers from profiting by their misconduct”). We also observe that in conspiracy cases, witnesses’ cooperation with the government threatens not only the liberty of the particular conspirators against whom the witness may testify, but the viability of the conspiracy as a whole; and an investigation or prosecution that might start with one conspirator may result in charges being levied against other conspirators as well. In sum, it would make little sense in a case such as this to parse the forfeiture doctrine as finely as Johnson proposes. We conclude that the district court reasonably found by a preponderance of the evidence that Johnson had forfeited her confrontation and hearsay objections to the admission of statements by Nicholson and DeGeus. 11. Commentary on Johnson’s post-arrest, post-Miranda warnings silence During the government’s merits-phase closing arguments, one of the prosecutors argued that if Johnson had been tricked by Honken into participating in the murders, as she essentially claimed, she would have said so when she spoke about the murders with various individuals. The prosecutor also displayed a chart during closing argument that read as follows: Gaubatz: no claim of innocence McNeese: no claim of innocence Bramow: no claim of innocence S. Johnson & W. Jacobson: no claim of innocence Baca: no claim of innocence Hoover: no claim of innocence Yager: no claim of innocence Johnson contends that the prosecutor’s remarks and his use of the chart was tantamount to improper commentary on her failure to testify and on her post-arrest silence. We disagree. We cannot see how any of the prosecutor’s remarks could be reasonably interpreted as a comment on Johnson’s decision to not testify. Johnson asserts that the prosecutor’s remarks implied that Johnson was under an obligation to proclaim her innocence, but that plainly was not what the prosecutor was arguing. The prosecutor was contending instead that the jury could infer, relying on its common sense understanding of human motivations, that if Johnson had been duped by Honken, she would have stressed that detail when she spoke with others about the crimes. As for the chart, we do not believe that it constitutes either a direct or indirect comment on Johnson’s failure to testify. Cf. Graham v. Dormire, 212 F.3d 437, 439 (8th Cir.2000) (stating that a prosecutor may not directly comment on a defendant’s failure to testify and that an indirect comment is impermissible if it manifests “the prosecutor’s intent to call attention to a defendant’s failure to testify or would be naturally and necessarily taken by a jury as a comment on the defendant’s failure to testify”). Nor was there improper commentary on Johnson’s post-arrest silence. Ordinarily, a defendant’s post-arrest, post-Miranda warnings silence may not be used against her. Doyle v. Ohio, 426 U.S. 610, 619-20, 96 S.Ct. 2240, 49 L.Ed.2d 91 (1976). The reasons for this rule are twofold: 1) such silence may be nothing more than an arrestee’s exercise of her constitutional rights; and 2) because the Miranda warnings carry an “implicit assurance” that an arrestee’s silence will not be used against her, using her silence would unfairly penalize her for relying on these assurances. United States v. Frazier, 408 F.3d 1102, 1110 (8th Cir.2005) (citing Doyle, 426 U.S. at 617-18, 96 S.Ct. 2240), cert. denied, 546 U.S. 1151, 126 S.Ct. 1165, 163 L.Ed.2d 1130 (2006). We have observed, however, that the “ ‘privilege against compulsory self-incrimination is simply irrelevant to a citizen’s decision to remain silent when [s]he is under no official compulsion to speak.’ ” Frazier, 408 F.3d at 1110 (quoting Jenkins v. Anderson, 447 U.S. 231, 241, 100 S.Ct. 2124, 65 L.Ed.2d 86 (1980) (Stevens, J., concurring)). In other words, “in determining whether the privilege [to remain silent] is applicable, the question is whether petitioner was in a position to have his testimony compelled and then asserted his privilege, not simply whether he was silent.” Jenkins, 447 U.S. at 244, 100 S.Ct. 2124 (Stevens, J., concurring). Thus, we concluded in Frazier that testimony regarding a defendant’s post-arrest, pre-Miranda silence does not necessarily constitute a Doyle violation because the mere fact of arrest does not itself give rise to a “government-imposed compulsion to speak” triggering the assertion of an ar-restee’s Fifth Amendment privilege. Frazier, 408 F.3d at 1111. Here, Johnson’s silence was not an exercise of her privilege to remain silent because she was under no official compulsion against which such a privilege would be asserted. Nor is there any reason to believe that Johnson was somehow relying on an implicit assurance by the government that her silence would not be used against her. Cf. Fletcher v. Weir, 455 U.S. 603, 606, 102 S.Ct. 1309, 71 L.Ed.2d 490 (1982) (per curiam) (“[W]e have consistently explained Doyle as a case where the government had induced silence by implicitly assuring the defendant that his silence would not be used against him”)- In sum, as the district court observed, “Johnson has not shown how, when, or why her right to remain silent had attached as to any of these witnesses.” Johnson, 403 F.Supp.2d at 828. 12. Merits-phase jury instructions Johnson’s next claim of error concerns the district court’s instructions to the jury pertaining to the merits phase of the trial. Johnson contends that the district court should have given her proposed jury instruction informing the jury that a mere buyer-seller relationship between Honken and others was not sufficient to show that Honken managed or supervised these individuals. We disagree. The district court’s instructions informed the jury that the prosecution was required to prove “that Dustin Honken exerted some type of influence over five or more other persons, as shown by these individuals’ compliance with his directions, instructions, or terms for performing the activities of the CCE.” We believe that these instructions adequately stated the law, as they largely tracked our description of the management element in Possick, 849 F.2d at 336. Moreover, the instructions gave Johnson room to argue that a mere buyer-seller relationship between Honken and others would be insufficient to make Honken a manager or supervisor over these individuals. Johnson also alleges various defects in the instructions relating to the predicate CCE offenses. Her principal complaint is that the articulation of several of these offenses, which tracks the language of the indictment, is so vague that it violated her right to a unanimous verdict on the predicate offenses underlying the CCE. The district court concluded that all of her complaints about the instructions as they pertain to the CCE predicates essentially reiterate objections to the indictment that it had already deemed waived as untimely. Johnson, 403 F.Supp.2d at 837. In any case, the instructions provide that each predicate offense must be found unanimously. Johnson appears to be contending that because several of the offenses were alleged to have occurred on unknown dates over an extended period of time, the jurors may have reached different conclusions regarding some of the facts underlying these offenses. Jurors may, however, differ on such “underlying brute facts” as long as they attain unanimity that a particular predicate offense occurred. Cf. Richardson v. United States, 526 U.S. 813, 817, 119 S.Ct. 1707, 143 L.Ed.2d 985 (1999) (noting the distinction between elements of the offense and the underlying facts of the offense). In a trial for a crime requiring the threat of force, for example, jurors could differ on whether a defendant used a knife or a firearm so long as they reached unanimity that the required element had been met. Id. Finally, even if the first seven alleged predicates about which Johnson complains were defective, the jury found five other offenses, thus rendering harmless any error. We have considered Johnson’s other allegations regarding the merits-phase jury instructions and conclude that they lack merit. 13. Johnson’s eligibility for the death penalty Johnson contends that she was not eligible for the death penalty for the murders of Lori Duncan or DeGeus because there was insufficient evidence that she personally committed the murders in a manner that involved torture or serious physical abuse. She also contends that she was not eligible for the death penalty for Lori Duncan’s murder because the evidence was insufficient to demonstrate that Lori Duncan’s murder involved torture or serious physical abuse. Johnson does not challenge on appeal the instructions the district court gave on the statutory aggravating factors, and she provides no authority for her suggestion that this aggravating factor required her to personally commit the murders. The instructions required the jury to find that Johnson “committed the offense in question in an especially heinous, cruel, or depraved manner in that it involved torture or serious physical abuse of the victim.” Although Johnson may not have pulled the trigger, the jury was warranted in concluding that her c