This is an opinion on a petition for rehearing, which raised several issues for our reconsideration. We granted the petition only with respect to alleged sentencing errors under
United States v. Booker,
543 U.S. —,
A jury found Defendant-Appellant Kenneth Wayne Stiger guilty of numerous counts of conspiring to possess and distribute narcotics. On appeal, he alleges seven grounds for us to find reversible error: (1) use of defective verdict forms; (2) a violation of
Apprendi v. New Jersey,
I. BACKGROUND
This appeal represents the culmination of the government’s investigation and prosecution of an extensive drug conspiracy. As the government proved at trial, the central player in the conspiracy was Darrell Bellamy of Phoenix, Arizona. From Phoenix, Mr. Bellamy coordinated shipments of powder cocaine, crack cocaine, and marijuana to various cities, including Tulsa, Oklahoma; Wichita, Kansas; and Detroit, Michigan.
At trial, several witnesses testified to Mr. Stiger’s involvement in the conspiracy. Specifically, these witnesses testified to seeing Mr. Stiger prepare marijuana for shipping, arrange for and assist in the transportation of marijuana and cocaine, and transfer and instruct others to transfer large amounts of money to Mr. Bellamy.
In addition to these general activities, Jennifer Natale testified that Mr. Stiger assisted three others in torturing her. Specifically, she testified that, in response to a dispute over the proceeds from a drug sale, Mr. Bellamy, two men identified only as Marvin and Dash, and another identified only as “Crazy Will,” forced her to remove her clothes below the waist and burned her repeatedly with a hot iron and with boiling grease. They also threatened to pour grease on her lap and face and to take her to the desert and shoot her. While the others tortured Ms. Natale, Mr. Stiger “held a gun at [her] head and he pushed it in [her] nose and he told [her] he was going to make it hurt.” 1
A federal grand jury indicted Mr. Stiger for conspiring to possess and. distribute cocaine, crack cocaine, and marijuana in violation of 21 U.S.C. § 846; conspiring to launder money in violation of 18 U.S.C. § 1956(h); and one count of forfeiture pursuant to 18 U.S.C. §§ 982 and 1956(h). After a twenty-three-day trial involving over fifty witnesses, a jury convicted Mr. Stiger on all counts. The District Court sentenced Mr. Stiger to life in prison to be followed by ten years’ supervised release and imposed $25,200 in fines and assessments. Mr. Stiger filed timely notice of appeal, raising seven issues. We address each below.
*1190 II. DISCUSSION
A. Verdict Forms
1. Standard of Review
Mr. Stiger first argues that the verdict forms used at trial were defective. We review verdict forms under the same “abuse of discretion standard we apply to jury instructions.”
United States v. Jackson,
Even if we conclude that the District Court erred, we must also determine whether the error is “harmless error.” Fed.R.Crim.P. 52(a). The government bears the burden to show that a nonconsti-tutional error is harmless by a preponderance of the evidence.
United States v. Wittgenstein,
2. Merits
Mr. Stiger contends that the verdict forms are defective because they did not require the jury to find him guilty of participating in the conspiracy before' it decided his guilt as to the objects of the conspiracy. Because the forms used by the District Court only required a finding as to the objects of the conspiracy, Mr. Stiger argues, “[i]n the case at bar we do not even have a conviction on the conspiracy count.” He therefore urges that the fundamental nature of this error mandates a new trial.
In response, the government claims that the verdict forms sufficiently informed the jury of the need to find Mr. Stiger guilty of the overarching conspiracy not just its objects. Noting that the jury “was given detailed instructions on the elements of the conspiracy charge and what it had to find in order to determine whether or not each defendant was guilty of conspiracy,” the government contends that we should interpret the verdict form in light of the instructions given. Understood in this light, the government argues, the verdict forms accurately informed the jury of the law.
Despite the government’s protestations, we agree with Mr. Stiger that the verdict forms never required the jury specifically to find him guilty of the overarching conspiracy. 2 Like Mr. Stiger, we read the verdict forms to require a finding only as to objects of the conspiracy.
*1191
Although we harbor grave doubts about the propriety of the use of these verdict forms, we need not decide whether their use constitutes error or whether the jury instructions cured any possible error because, even if we found error, the use of the verdict forms did not substantially influence the outcome of the trial.
See United States v. Magleby,
The government carries its burden to establish harmlessness by pointing to the testimony of at least fourteen witnesses who offered testimony against Mr. Stiger. Several witnesses testified at length to his involvement in packaging and coordinating shipments of drugs for the conspiracy and in sending large amounts of money to Mr. Bellamy. We are especially persuaded by Ms. Natale’s extensive and gruesome testimony regarding Mr. Stiger’s involvement in her torture. As she made clear in her testimony, this torture was directly related to a dispute about the proceeds from a drug sale for the conspiracy. In light of this testimony, we find that the alleged verdict-form error did not substantially impact the outcome of the trial. 3
B. Sentencing
1. Standard of Review
Mr. Stiger next argues that the District Court violated his Sixth Amendment rights by not requiring the jury to make a specific finding as to the amount of drugs for which he was personally responsible. Because Mr. Stiger made this constitutional argument at sentencing, we review the issue de novo.
United States v. Lampley,
2. Merits
Below, the Government, in accordance with 21 U.S.C. § 851(a), notified Mr. Stiger that it would seek the application of 21 U.S.C. § 841(b)(1)(A). “Section 841(b)(1)(A) requires imposition of a ‘mandatory term of life imprisonment without release’ if (1) a defendant is convicted of violating § 841(a), (2) that conviction involved a certain requisite amount of drugs, and (3) the crime was committed ‘after two or more prior convictions for a felony drug offense have become final.’ ”
United States v. Harris,
*1192 At sentencing, -Mr. Stiger objected to the jury’s finding as to drug type and amount for the entire conspiracy, arguing that Apprendi and now, Booker, require the jury also to make specific findings as to the amount and type of drug attributable to him individually. 4 The District Court concluded that Apprendi does not require the jury in a conspiracy case to make individual findings as to each member of the conspiracy, determined Mr. Stiger was integral to the conspiracy and could be sentenced as though he were responsible for the full drug types and quantities, found that Mr. Stiger had two previous felony drug convictions, and therefore sentenced him to life imprisonment. See 21 U.S.C. § 841(b)(1)(A). On appeal, Mr. Stiger raises two objections to the application of § 841(b)(1)(A).
First, Mr. Stiger argues that
Ap-prendi
and
Booker
require the jury, rather than the judge, to determine whether he had two prior felony drug convictions. In essence, he asserts that
Booker
overrules
Almendarez-Torres v. United States,
The second issue Mr. Stiger raises — whether a jury, after
Apprendi
and
Booker,
must determine the amount and type of drug attributable to individual eo-conspirators rather than simply attributable to the entire conspiracy — is one of first impression before this Court. Prior to
Booker,
however, at least five other circuits addressed it; each held that
Ap-prendi
only requires the jury to make a finding, beyond a reasonable doubt, as to the amount of drugs for which the entire conspiracy is liable.
See United States v. Phillips,
The reasoning of these courts is simple. First,
Apprendi
held that “[ojther than the fact of a prior conviction, any fact that increases the penalty for a crime beyond the prescribed statutory maximum must be submitted to a jury, and proved beyond a reasonable doubt.”
Apprendi,
*1193
We agree with the reasoning of our sister circuits that
Apprendi
requires the jury only to set the “maximum sentence ( [i.e., the] ceiling)” under which each cocon-spirator’s sentence must fall.
See Knight,
We also conclude that
Booker
does not call this practice into question. The primary innovation that the Court introduced in
Booker
was to clarify what the term “statutory maximum” means for
Apprendi
purposes. “Our precedents ... make clear that the ‘statutory maximum’ for
Ap-prendi
purposes is the maximum sentence a judge may impose solely on the basis of the facts reflected in the jury verdict or admitted by the defendant.”
Booker,
Our analysis of the constitutionality of Mr. Stiger’s sentence might be different if the District Court had relied upon judge-found facts and the U.S. Sentencing Guidelines, instead of § 841(b)(1)(A), to sentence Mr. Stiger to life imprisonment. Here, the record is not clear whether the District Court sentenced under the Guidelines, and thus relied upon judge-found facts in the context of a mandatory sentencing regime, or § 841(b)(1)(A).
See
R. Vol. XXXVIII at 26 (sentencing Mr. Stiger “under the law and the guidelines”). Nonetheless, even if we assume the District Court erroneously found facts and mandatorily applied the Guidelines,
see Gonzalez-Huerta,
C. Sufficiency of the Evidence
1. Standard of Review
Following the presentation of the government’s case, Mr. Stiger moved for a judgment of acquittal pursuant to Fed. R.Crim.P. 29, alleging insufficient evidence. “We review the sufficiency of the evidence de novo.”
United States v. Overholt,
2. Merits
Mr. Stiger contends that the District Court erred in denying that motion because the government introduced insufficient evidence to prove that he was a member of the alleged drug conspiracy. Although conceding that the drug conspiracy existed, he argues that the government failed to prove that he “had a specific intent to join the Darrell Bellamy conspiracy.” To this end, he asserts that the government failed to introduce evidence that he was a member of the Bellamy conspiracy and that, at most, it only “proved that [he] was involved in drug distribution and that he and [Mr.] Bellamy had overlapping drug involvement.” Inexplicably — and seemingly in conflict with his recitation of facts — he also concludes that he “was never involved with the Jennifer Natale torture episode.”
The record wholly belies Mr. Stiger’s assertions that insufficient evidence exists to prove his membership in the Bellamy conspiracy. See supra p. 1189. As the government illustrates in its brief, and we confirmed upon our independent review of the record, substantial evidence was presented showing that Mr. Stiger “knew the objective of the conspiracy was to profit from the distribution of illegal drugs, that he voluntarily participated, ... that he acted to further the objectives of the conspiracy,” and that he “took essential and integral steps to help the organization profit from the sale of illegal drugs.” We therefore affirm the District Court’s decision to deny Mr. Stiger’s motion for judgment of acquittal.
D. Mistrial
1. Standard of Review
Mr. Stiger moved for a mistrial below. In determining whether to grant a mistrial, a district judge must first determine whether an error has occurred and, if so, whether that error impaired the “defendant’s right to a fair and impartial trial.”
United States v. Meridyth,
2. Merits
Well into the trial, Mr. Stiger’s counsel moved for a mistrial based on the fact that attorney Robert Burton visited with him on several occasions about representing him in this ease. The visits were unfruitful for Mr. Burton, as the District Court ultimately appointed another attorney to represent Mr. Stiger. The District Court, however, appointed Mr. Burton and his law partner to represent Richard Taylor, one of Mr. Stiger’s codefendant’s. Mr. Taylor entered a guilty plea prior to Mr. Stiger’s arraignment and became a witness for the government at Mr. Stiger’s trial. Mr. Burton continued to represent Mr. Taylor throughout the course of this testimony.
Mr. Stiger’s trial counsel claims that he was not initially aware of Mr. Burton’s conversations with Mr. Stiger. Upon learning of these conversations, however, trial counsel moved for a mistrial based upon a conflict of interest. Trial counsel stated that Mr. Burton “visited [his] client *1195 three times before th[e] trial started” and that the two spoke “several times about the case,” although he could not say with certainty whether those conversations would prejudice his client. Counsel sought an evidentiary hearing to determine whether an attorney-client relationship existed between Messrs. Stiger and Barton. The District Court denied the mistrial motion without conducting an evidentiary hearing.
On appeal, Mr. Stiger argues that the District Court should have conducted this evidentiary hearing before dismissing his conflict-of-interest claim. He asserts that the summary dismissal of his mistrial request based on the asserted conflict without hearing or further inquiry violated his rights to due process, confrontation of witnesses, and conflict free counsel. As such, Mr. Stiger asks us to reverse his conviction.
In response, the government asserts that Mr. Burton never represented Mr. Stiger and that a new trial would gain Mr. Stiger nothing because his remedy would be a new trial in which co-defendant Taylor would again testify. 5
Two sources inform whether a district court should disqualify an attorney. “First, attorneys are bound by the local rules of the court in which they appear .... Second, because motions to disqualify counsel in federal proceedings are substantive motions affecting the rights of the parties, they are decided by applying standards developed under federal law.”
Cole v. Ruidoso Mun. Schools,
The United States District Court for the Northern District of Oklahoma has adopted the Oklahoma Rules of Professional Conduct.
6
Here, Oklahoma Rule of Professional Conduct Rule 1.9 provides the relevant rule.
7
Oklahoma Rule 1.9 tracks exactly the text of Rule 1.9 of the ABA Model Rules of Professional Conduct,
*1196
which “we believe reflect[s] the national standard to be used in ruling on disqualification motions.”
Cole,
Under Rule 1.9, a party seeking to disqualify opposing counsel must establish that “(1) an actual attorney-client relationship existed between the moving party and the opposing counsel; (2) the present litigation involves a matter that is ‘substantially related’ to the subject of the movant’s prior representation; and (3) the interests of the opposing counsel’s present client are materially adverse to the mov-ant.”
Cole,
To show that an attorney-client relationship existed, Mr. Stiger need not show that “the parties ... executed a formal contract” or that he paid fees.
Cole,
In applying the second prong — the “substantial relation” test — we look to whether “the factual contexts of the two representations are similar or related.”
Smith,
Here, Mr. Stiger made a non-frivolous allegation before the District Court that Mr. Barton and he had an attorney-client relationship in a substantially related matter. We find that the District Court abused its discretion by failing to investigate this allegation further through an evidentiary hearing. Because we lack essential factual predicates to conduct a disqualification analysis, we cannot pass on the merits of Mr. Stiger’s claim on appeal. As such, we remand this issue to the District Court with instructions to hold an evidentiary hearing in accord with this opinion. If, following this hearing, the District Court concludes that an attorney-client relationship existed between Messrs. Burton and Stiger, it should then determine whether the representation affected Mr. Stiger’s “right to a fair and impartial trial.”
Meridyth,
E. Severance
1. Standard of Review
Mr. Stiger next argues that the District Court erred in refusing to sever *1197 his trial from those of his alleged cocon-spirators because the government sought to introduce highly prejudicial evidence of codefendant Marlin Mack’s alleged murdering of two people. In United States v. Evans, we held that:
The decision whether to grant a severance is within the sound discretion of the trial court. We will not disturb the trial court’s decision absent an affirmative showing of abuse of discretion and a strong showing of prejudice. To establish abuse of discretion more is required than that separate trials might have offered a better chance for acquittal of one or more of the accused.970 F.2d 663 , 676 (10th Cir.1992) (internal citations and quotations omitted) (emphasis added).
Furthermore, Mr. Stiger must overcome the presumption that “in a conspiracy trial it is preferred that persons charged together be tried together.”
United States v. Scott,
2. Merits
Pointing to a list of evidence, Mr. Stiger concludes that the “cumulative and prejudicial impact” of that testimony requires severance. Noting the strong preference for joint trials of coconspirators, the government argues that, as a member of the conspiracy, Mr. Stiger was liable for its violent acts. Moreover, the government asserts that Mr. Stiger was himself heavily involved in the violent torture of Ms. Natale. Further, the government contends that he suffered no prejudice from the denial of severance.
Mr. Stiger cannot establish reversible error. Even if he could show that the District Court abused its discretion in denying his motion to sever, he cannot make “a strong showing of prejudice.”
Evans,
F. Summary Witness Testimony
1. Standard of Review
Mr. Stiger next argues that the District Court erred in allowing Officer Harold Adair to present summary testimony and exhibits. “We review a district court’s evidentiary rulings for abuse of discretion.”
United States v. Curtis,
*1198 2. Merits
Mr. Stiger challenges the admission of five exhibits and the accompanying testimony. First, Mr. Stiger objects to a chart offered by Officer Adair that purported to detail the organizational structure of the conspiracy. Officer Adam testified that he constructed this chart both from trial testimony and from interviews conducted during the investigation. On appeal, ,Mr. Stiger reasserts his contention that Officer Adair gleaned much of his testimony from sources not admitted at trial. As such, he urges that the summary testimony and charts were inadmissable hearsay. In response, the government claims that the District Court properly admitted the testimony and charts as expert testimony pursuant to Fed.R.Evid. 702. The government also notes that many courts have allowed summary testimony and charts pursuant to Fed.R.Evid. 611(a), finding them to be helpful to the jury.
As this Court has noted, a party may only admit summary testimony under Fed.R.Evid. 611(a) if the District Court previously admitted at trial the evidence that forms the basis of the summary.
See United States v. Ray,
Second, Officer Adair offered a time line illustrating the trips taken by the members of the conspiracy and the specific drugs transported on those trips. Officer Adair testified that he prepared the time line solely from evidence admitted at trial. Mr. Stiger did not object to the admission of the time line, but did object to a portion of Officer Adair’s accompanying testimony as going beyond the evidence admitted at trial. The District Court sustained that objection, re-instructed the government that “[t]his is a summary of the evidence, not a summary of the investigation,” and redacted the objected-to evidence. Because the District Court sustained Mr. Stiger’s objection at trial, there is no error to correct on appeal.
Third, Officer Adair offered a chart of the total drug amounts testified to at trial. He testified that the chart was based exclusively on evidence admitted at trial. Mr. Stiger lodged an ambiguous objection against the chart. Reviewing the record evidence, we find that the District Court properly admitted the chart pursuant to Fed.R.Evid. 611(a) because it was undoubtedly helpful to the jury in this particularly complex case, the District Court offered extensive limiting instructions, and the chart was based exclusively on previously admitted evidence.
See Ray,
Finally, Officer Adair offered two other charts, one detailing the specific drug amounts attributable to each defendant and another illustrating the drug prices charged by the conspiracy in various transactions. He testified that both
*1199
charts were based exclusively on previously admitted evidence. Mr. Stiger did not object to the introduction of either chart nor to the accompanying testimony at trial. “We review the district court’s ruling admitting evidence ... if no objection is made, for plain error.”
United States v. Castorena-Jaime,
G. Speedy Trial Act
1. Standard of Review
Finally, Mr. Stiger argues that the District Court erred in concluding that the Speedy Trial Act, 18 U.S.C. § 3161 et seq., does not apply to an information filed pursuant to 21 U.S.C. § 851(a)(1). We review the District Court’s interpretation of this statute de novo.
United States v. Alahmad,
2. Merits
On April 30, 2002, the government filed an information pursuant to § 851(a)(1), notifying Mr. Stiger of its intent to use his prior felony convictions to enhance any sentence resulting from the current prosecution. On July 11, 2002, Mr. Stiger filed a motion to dismiss this information, claiming that the Speedy Trial Act required the government to commence trial against him on the § 851(a)(1) information within seventy days of its filing. The District Court denied his motion, finding that the “plain language” of the “Speedy Trial Act only applies to informa-tions and indictments which charge ‘the commission of an offense.’ ” For the reasons provided in a companion case, we affirm the District Court’s Speedy Trial Act ruling.
See United States v. Vaughn,
III. CONCLUSION
Therefore, we AFFIRM the judgment of the District Court except as to the mistrial claim, which we REVERSE and REMAND with instructions to hold an eviden-tiary hearing in accordance with this opinion. Our opinion in Stiger I is VACATED.
Notes
. Although not entirely clear, Mr. Stiger appears to concede these facts in his appellate brief.
. The pertinent forms read:
Count 1 — charges a drug conspiracy in violation of Title 21, United States Codes[s][sic], Section 846. We, the Jury, in the above styled and numbered case do upon our oaths, unanimously find the defendant Kenneth Wayne Stiger as to Count 1, as follows:
Object 1 — Knowingly and intentionally distribute and possess with intent to distribute a mixture or substance containing a detectable amount of cocaine in violation of 21 U.S.C. § 841(a)(1):
__ Not Guilty_X__ Guilty
Object 2 — Knowingly and intentionally distribute and possess with intent to distribute a mixture or substance containing a detectable amount of marijuana in violation of 21 U.S.C. § 841(a)(1):
.__ Not Guilty_X Guilty
Object 3 — Knowingly and intentionally distribute and possess with intent to distribute a mixture or substance containing a detectable amount of cocaine base (crack cocaine) in violation of 21 U.S.C. § 841(a)(Z):
_ Not Guilty X Guilty
*1191 As previously instructed, only if you find one or more of the defendants now on trial “guilty” of Count 1, will you proceed to make a determination regarding the amount of controlled substance attributed to each object of the conspiracy charged in the Second Superseding Indictment. If, on the other hand, you find all of the defendants now on trial "not guilty” of Count 1, then you need not consider Verdict Form-6.
. To be clear, we do not approve of the District Court’s use of the verdict forms at issue. The District Court should have employed forms that required a finding as to guilt for the conspiracy. Rather, we hold only that any resulting error did not affect the outcome of the trial as required by Rule 52(a) of the Federal Rules of Criminal Procedure.
. Had this occurred, Mr. Stiger appears to contend, he would not have been subject to the ten-year or life mandatory minimum because § 841(b)(1)(B) provides for a mandatory minimum of only five years' imprisonment for trafficking in lesser quantities of controlled substances and only ten years if there is a prior felony drug conviction.
. On appeal, the government has not argued that Mr. Stiger’s claim is essentially an untimely motion to disqualify, which we would review for plain error. Thus, we assume for purposes of this appeal that Mr. Stiger timely raised this issue in the context of a mistrial motion during trial.
. See N.D. Okla. R. 83.2 (“Attorneys practicing in this court are expected to conduct themselves in accordance with the Oklahoma Rules of Professional Conduct, as adopted by the Oklahoma Supreme Court, as the standard of conduct of all members of the Oklahoma Bar Association.”); see also N.D. Okla. R. 83.4 (oath requiring an attorney to "solemnly swear” to "be bound by the Oklahoma Rules of Professional Conduct and [to] conduct [himself] in compliance therewith at all times.”).
. This rule reads:
(a)A lawyer who has formerly represented a client in a matter shall not thereafter represent another person in the same or a substantially related matter in which that person’s interests are materially adverse to the interests of the former client unless the former client consents after consultation.
(b) A lawyer shall not knowingly represent a person in the same or a substantially related matter in which a firm with which the lawyer formerly was associated had previously represented a client
(1) whose interests are materially adverse to that person; and
(2) about whom the lawyer had acquired information protected by Rules 1.6 and 1.9(c) that is material to the matter; unless the former client consents after consultation.
(c) A lawyer who has formerly represented a client in a matter or whose present or former firm has formerly represented a client in a matter shall not thereafter:
(1) use information relating to the representation to the disadvantage of the former client except as Rule 1.6 or Rule 3.3 would permit or require with respect to a client, or when the information has been generally known; or
(2) reveal information relating to the representation except as Rule 1.6 or Rule 3.3 *1196 would permit or require with respect to a client.
. Although we have subsequently modified
Smith
as it applies to imputing a conflict to an entire firm,
see SLC Ltd. v. Bradford Group West, Inc.,
. Mr. Stiger, for the first time on appeal, also argues that the admission of the summary testimony violated his Sixth Amendment right "to be confronted with the witnesses against him.” U.S. Const, amend. VI. Because he never raised that objection before the District Court, we review it for plain error.
United States v. LaHue,
