Introduction

This Tenth Circuit appeal arises from a fatal shooting on the Wind River Indian Reservation in Wyoming. The defendant, Francis James Acebo, Jr., claimed self-defense after shooting his neighbor, Derek Redstar Pappan, in the back of the head during a night of drinking when tensions and suspicions escalated. A jury convicted Acebo of murder in Indian country, using a firearm during a crime of violence, and causing death through the use of a firearm. The district court imposed concurrent life sentences on the murder-related counts and a consecutive ten-year sentence on the firearm count.

On appeal, Acebo challenged four trial management and evidentiary rulings: (1) exclusion of “reverse 404(b)” evidence of the victim’s prior bad acts; (2) limits on cross-examination of a key witness, Mia Brown, including impeachment with a prior statement; (3) restriction on cross-examination regarding the victim’s toxicology results; and (4) refusal to hold an evidentiary hearing into alleged juror coercion and a deliberation-room medical incident under Federal Rule of Evidence 606(b).

The Tenth Circuit affirmed across the board. Two practical holdings stand out for litigants and trial judges: first, district courts may enforce scheduling orders that require reciprocal Rule 404(b) notice by any party and may affirm evidentiary exclusions based on noncompliance; second, juror medical intervention during deliberations does not, without more, constitute an “outside influence” that triggers a Remmer hearing or an exception to Rule 606(b)’s bar on probing jury deliberations.

Summary of the Opinion

• Reverse 404(b) evidence: The district court excluded defense evidence of the victim’s prior bad acts. The Tenth Circuit affirmed without reaching the merits of admissibility because the defendant failed to comply with a Discovery and Scheduling Order requiring any party to give advance notice of Rule 404(b) (and Rule 807) evidence. The court relied on the principle that it may affirm on any ground supported by the record.
• Cross-examination limits and Confrontation Clause: The district court properly barred impeachment of witness Mia Brown with a prior statement suggesting the victim had threatened the defendant, because the statement was not truly inconsistent with Brown’s trial testimony and, given the absence of evidence that the defendant was aware of the threat, the probative value was substantially outweighed by risks identified in Rule 403. The Confrontation Clause claim failed because it was underdeveloped and did not meaningfully engage the district court’s reasons.
• Toxicology/hearsay: The district court sustained hearsay and relevance objections to cross-examining the coroner about methamphetamine in the victim’s system where the coroner did not perform the toxicology test. On appeal, the defendant inadequately briefed any hearsay exception (citing Rules 803(4) and 803(8) in a single sentence), thereby waiving the argument.
• Juror letter and Rule 606(b): The court rejected the request for a post-verdict evidentiary hearing into juror misconduct. The juror’s post-verdict email described internal deliberation dynamics (hostility, pressure, heat in the room, a panic attack and medical treatment), not an “outside influence” or “extraneous prejudicial information.” Because Rule 606(b) bars inquiry into internal deliberations, and Remmer applies only to external influences, the district court acted within its discretion in declining to hold a hearing after a sealed disclosure proceeding with both parties.

Analysis

Precedents Cited and Their Roles

• Richison v. Ernest Group, Inc., 634 F.3d 1123 (10th Cir. 2011) (Gorsuch, J.), and United States v. Davis, 339 F.3d 1223 (10th Cir. 2003): The Tenth Circuit may affirm on any basis supported by the record, including grounds not reached below. This allowed affirmance of the Rule 404(b) ruling for failure to comply with the scheduling order’s notice requirement, without adjudicating whether the proposed “reverse 404(b)” evidence would have been admissible.
• Standards of review for evidentiary rulings:
  • United States v. Tony, 948 F.3d 1259 (10th Cir. 2020); United States v. Ramone, 218 F.3d 1229 (10th Cir. 2000): abuse-of-discretion review governs evidentiary exclusions.
  • United States v. Williams, 934 F.3d 1122 (10th Cir. 2019); United States v. Hall, 473 F.3d 1295 (10th Cir. 2007); United States v. Silva, 889 F.3d 704 (10th Cir. 2018); Ralston v. Smith & Nephew Richards, Inc., 275 F.3d 965 (10th Cir. 2001): define abuse of discretion and articulate when a ruling is arbitrary, capricious, or manifestly unreasonable.
  • United States v. Tan, 254 F.3d 1204 (10th Cir. 2001): articulates Rule 403 balancing.
• Confrontation and cross-examination:
  • United States v. Markey, 393 F.3d 1132 (10th Cir. 2004), citing Rock v. Arkansas, 483 U.S. 44 (1977): recognizes the right to present a defense and cross-examine adverse witnesses.
  • Delaware v. Van Arsdall, 475 U.S. 673 (1986): trial courts retain wide latitude to limit cross-examination to avoid harassment, confusion, prejudice, and marginally relevant interrogation.
  • Nixon v. City & County of Denver, 784 F.3d 1364 (10th Cir. 2015): an appellant cannot show reversible error without challenging the district court’s actual reasons; applied to reject the underdeveloped Confrontation Clause claim.
• Waiver by inadequate briefing:
  • Tachias v. Sanders, 130 F.4th 836 (10th Cir. 2025), quoting Burke v. Regalado, 935 F.3d 960 (10th Cir. 2019) and Bronson v. Swensen, 500 F.3d 1099 (10th Cir. 2007): cursory assertions without developed analysis waive the issue on appeal; used to dispose of the hearsay-exception argument.
• Rule 606(b) and juror inquiries:
  • United States v. Humphrey, 208 F.3d 1190 (10th Cir. 2000) and United States v. Davis, 60 F.3d 1479 (10th Cir. 1995): whether and how to hold a hearing about exposure to extraneous information lies in the trial court’s discretion.
  • Remmer v. United States, 347 U.S. 227 (1954): requires an evidentiary hearing when credible allegations show a juror was subject to external attempt at influence (e.g., bribery); distinguished here because no external contact was alleged.
  • United States v. Miller, 806 F.2d 223 (10th Cir. 1986); United States v. Cattle King Packing Co., Inc., 793 F.2d 232 (10th Cir. 1986): Rule 606(b) forbids inquiry into internal deliberative processes absent extraneous information, outside influence, or a verdict-form error.
  • Tanner v. United States, 483 U.S. 107 (1987), citing Government of V.I. v. Nicholas, 759 F.2d 1073 (3d Cir. 1985): warns against post-verdict intrusions into jury deliberations and underscores the policy of verdict finality; applied to reject post-verdict juror second thoughts and internal dynamics as grounds for relief.
  • Arizona v. Gant, 556 U.S. 332 (2009): noted only for abrogation of a point in Humphrey on other grounds; not central to the holding.

Legal Reasoning

1) Reciprocal Rule 404(b) Notice and Exclusion for Noncompliance

The district court’s Discovery and Scheduling Order required “any party” intending to introduce evidence under Rules 404(b) or 807 to provide written notice at least 14 days before trial. Rule 404(b)(3) by its text obligates the government to provide notice when the government intends to use other-acts evidence; the Scheduling Order extended that obligation reciprocally to the defense. Acebo did not file the required notice. The Tenth Circuit held that noncompliance with this enforceable case-management order supported exclusion and obviated the need to decide the substantive admissibility of the defense’s “reverse 404(b)” evidence. Invoking Richison, the court affirmed on this ground even though the district court had not specified it as the sole basis.

Notably, the panel rejected the defense position that the evidence fell outside Rule 404(b). The court emphasized that Rule 404(b) covers “other crimes, wrongs, or acts,” regardless of whether proffered for permissible or impermissible purposes. Because the defense sought to introduce the victim’s prior acts to establish the defendant’s state of mind, the evidence squarely triggered the Order’s 404(b) notice requirement. The failure to give notice undermined any abuse-of-discretion argument against exclusion.

2) Limits on Cross-Examination and Impeachment: No Inconsistency, Rule 403, and Confrontation

Defense counsel asked Mia Brown whether she knew of anything in the relationship between Acebo and Pappan that might make either fearful; she said no. The defense sought to impeach with a prior statement in which Brown recounted that the victim once said he would “take out” the defendant or his children. The panel upheld exclusion on two grounds:

• No prior inconsistency: The court concluded the prior statement did not contradict Brown’s in-court answer on this record because the defense neither introduced nor proffered evidence showing Acebo knew of that threat. Without defendant’s awareness, the prior statement did not undermine Brown’s in-court testimony about what she knew that would cause fear.
• Rule 403 balancing: Given the lack of evidence that Acebo was aware of the threat, the marginal probative value of the prior statement on the issues at trial was substantially outweighed by risks of unfair prejudice, confusion, and waste of time.

The Confrontation Clause argument failed because it was first raised on appeal and, critically, did not engage with the district court’s actual Rule 403 reasoning. Under Nixon, an appellant cannot establish reversible error without challenging the reasons provided for the ruling. The opinion also reiterated Van Arsdall’s core lesson: trial courts have wide latitude to manage and cabin cross-examination to ensure relevance, clarity, and fairness.

3) Toxicology Cross-Examination: Hearsay and Waiver

The coroner’s autopsy documented the cause of death as a gunshot wound to the head. Although the toxicology report showed methamphetamine in the victim’s system, the test was performed by another entity. The district court sustained hearsay and relevance objections when the defense sought to cross-examine the coroner about the drug’s effects. On appeal, the defense referenced Rules 803(4) (medical diagnosis/treatment) and 803(8) (public records) in a single sentence without developing how those exceptions would admit either the toxicology report or derivative testimony. Relying on Tachias, Burke, and Bronson, the panel held the argument was inadequately briefed and therefore waived.

4) Juror Panic Attack, Post-Verdict Email, and Rule 606(b): No External Influence, No Remmer Hearing

After returning guilty verdicts, Juror #32 emailed a state court clerk (later forwarded to the federal court) expressing post-verdict doubts, describing a panic attack during deliberations, hostile deliberation-room dynamics, and even fear of other jurors. The district court held a sealed proceeding with both parties to disclose the email and concluded Rule 606(b) barred further inquiry because the allegations concerned internal deliberations and conditions, not external influences or extraneous information. The Tenth Circuit agreed:

• Internal vs. external: Allegations of pressure by fellow jurors, heated atmosphere, physical conditions (e.g., a hot room), or a juror’s medical emergency are internal matters that Rule 606(b) shields from judicial inquiry. No juror reported contact with outsiders, exposure to extraneous information, or a clerical error on the verdict form.
• Medical personnel are not “outside influence” on this record: The defense characterized the presence of emergency medical personnel as an “external influence.” The court found no allegation—let alone evidence—connecting medical treatment to deliberative decision-making or the verdict. Juror #32 remained on the panel voluntarily and suggested he stayed despite the incident. Absent a credible nexus to improper influence, Rule 606(b) controlled, and Remmer did not apply.
• Process mattered: Unlike Remmer’s ex parte action, the district court included both parties in a sealed disclosure. Given the discretionary standard (Humphrey, Davis) and the finality concerns emphasized in Tanner, the refusal to hold an evidentiary hearing was well within the trial court’s “wide latitude.”

Impact and Practical Implications

A. Discovery and Trial Management

• Reciprocal Rule 404(b) notice is enforceable: Even though Rule 404(b)(3) expressly mentions the government’s notice duty, district courts can require reciprocal notice by scheduling order. Noncompliance can justify exclusion without reaching admissibility. Defense teams intending to offer “reverse 404(b)” or victim-trait evidence should treat local orders as mandatory and calendar deadlines accordingly.
• Preserve all bases for admissibility: If the defense believes evidence falls under Rule 404(a)(2) (victim’s pertinent trait) or Rule 405(b) (specific instances where character is an essential element), it should say so explicitly and in time, while also complying with any 404(b) notice the court has imposed. The Acebo panel took a text-based approach: other-acts evidence triggers the notice requirement regardless of the proponent’s ultimate purpose.

B. Cross-Examination and Impeachment Strategy

• Show defendant’s knowledge to link victim threats to state of mind: Where a self-defense theory depends on prior threats, build a record that the defendant knew of them. Without that link, the probative chain to reasonableness of fear is weak and Rule 403 exclusion becomes likely.
• Impeachment via prior inconsistent statements requires true inconsistency: General questions at trial and context-laden prior statements often pass in the night. Frame questions precisely and secure foundation for contradiction. Otherwise, a Rule 403 assessment may readily outweigh marginal impeachment value.
• Confrontation Clause claims must engage the trial court’s reasoning: On appeal, address each ground the court gave (e.g., Rule 403) and explain why the limits were not “reasonable” under Van Arsdall. Undeveloped constitutional claims will fail.

C. Scientific Evidence and Hearsay

• Identify and brief the exact hearsay pathway: If the testifying witness did not perform the analysis, prepare to use an applicable exception (e.g., public records under Rule 803(8), business records under Rule 803(6), or call the analyst). On appeal, develop the doctrinal and factual predicates; cursory citations risk waiver.
• Relevance beyond cause of death: Toxicology may be relevant to reasonableness of perceived danger, but admissibility depends on a non-hearsay method or a valid exception and a witness with a proper foundation to explain pharmacological effects.

D. Juror Issues, Rule 606(b), and Remmer

• Differentiate internal dynamics from external influence: Heat in the room, juror conflicts, fear of fellow jurors, medical events, and a juror’s remorse are internal and generally off-limits under Rule 606(b). An evidentiary hearing is warranted only for extraneous information or genuine outside influence.
• Document a causal nexus for any alleged external influence: If medical personnel, court security, or third parties interact with jurors, provide specific, timely evidence that the contact touched on the case or affected deliberations. Without such a link, Remmer does not apply.
• Prompt, structured procedures matter: The district court’s sealed disclosure with both parties present exemplifies a measured response that respects verdict finality while informing the parties. Post-verdict juror emails expressing doubt rarely justify reopening deliberations (Tanner).

Complex Concepts Simplified

• Rule 404(b) and “reverse 404(b)”: Rule 404(b) governs evidence of “other crimes, wrongs, or acts.” It typically appears when the government wants to use a defendant’s prior acts. “Reverse 404(b)” refers to a defendant offering someone else’s prior acts (often a victim or third party) to show, for example, the defendant’s state of mind. Even when used for a permissible purpose, courts can impose advance notice requirements and still exclude the evidence under Rule 403.
• Rule 404(a)(2) vs. Rule 404(b): In self-defense cases, a defendant may offer evidence of a victim’s violent character as a “pertinent trait” under Rule 404(a)(2). But the mode of proof (reputation, opinion, or specific acts) is controlled by Rule 405. If the proponent instead offers specific past acts as “other-acts” proof, Rule 404(b), any court-ordered notice, and Rule 403 all apply.
• Rule 403 balancing: Judges may exclude evidence if its probative value is substantially outweighed by the danger of unfair prejudice, confusion, misleading the jury, undue delay, or wasting time.
• Abuse of discretion: Appellate courts defer to trial judges on evidentiary management and will overturn only if the ruling was arbitrary, capricious, or based on legal or factual error.
• Waiver by inadequate briefing: On appeal, arguments need more than a citation; they require analysis applying the facts to the rule. Bare assertions are treated as waived.
• Rule 606(b): After a verdict, courts generally cannot consider juror testimony about what happened during deliberations. Three exceptions exist: extraneous prejudicial information, outside influence, or a clerical mistake entering the verdict. Internal pressure, heated arguments, or juror remorse are not exceptions.
• Remmer hearings: If there is a credible allegation that outsiders tried to influence a juror (for example, a bribe), the court typically must hold a hearing. Remmer does not apply to internal deliberation dynamics or medical emergencies absent a connection to improper influence.

Conclusion

United States v. Acebo reinforces two pragmatic messages for trial practice in the Tenth Circuit. First, district courts may require reciprocal notice of Rule 404(b) and Rule 807 evidence by pretrial order and enforce that order through exclusion, even when the evidence is proffered by a criminal defendant as “reverse 404(b).” Compliance with scheduling orders is thus critical to preserving defensive evidence aimed at state-of-mind or self-defense theories. Second, Rule 606(b)’s bar on probing jury deliberations remains robust: juror distress, pressure, and even medical interventions during deliberations are internal matters that do not trigger a Remmer hearing absent a concrete allegation of an external influence or extraneous information.

The opinion also underscores familiar but vital appellate lessons: develop Confrontation Clause and hearsay-exception arguments with specificity; anchor impeachment to true inconsistencies; and ensure that evidence offered to show the defendant’s state of mind is accompanied by proof the defendant knew the underlying facts. Although designated nonprecedential, Acebo will have persuasive force in future cases on discovery management for 404(b) evidence and on the strict limits of post-verdict juror inquiries.