Rule 404(b) Allows Prior Surreptitious “Peeping” Videos to Prove Identity by Voice Comparison and to Rebut “Accidental Recording” Claims

Case: United States v. Bycroft (No. 24-7069) — Court: U.S. Court of Appeals for the Tenth Circuit — Date: May 5, 2026

I. Introduction

United States v. Bycroft is a Federal Rule of Evidence 404(b) decision arising from a child-pornography production prosecution. Heather Nicole Bycroft was tried for offenses tied to three “pool videos” found on her husband Jason’s Dropbox account, depicting a six-year-old girl at a 2015 family gathering, including footage where the child’s shorts/underwear are moved and her genitalia are exposed to the camera. Bycroft is not visible in the pool videos; the prosecution’s identity theory relied heavily on a female camera-operator voice in two of them.

The central evidentiary dispute was whether the government could introduce, as “other acts” evidence under Rule 404(b), several later “Peeping Tom videos” (recorded in public locations such as store dressing rooms) in which Bycroft and Jason intentionally positioned a camera to see up adult women’s skirts. These videos included Bycroft’s identifiable features (face at times, wedding ring, leg tattoo) and her audible voice.

Key issues: (1) whether the Peeping Tom videos were relevant to the charged conduct (Rule 402/Huddleston relevance through similarity), and (2) whether they were admitted for permissible, non-propensity purposes—particularly identity and absence of mistake/accident.

II. Summary of the Opinion

The Tenth Circuit affirmed the conviction, holding the district court did not abuse its discretion by admitting three Peeping Tom videos under Rule 404(b). The panel agreed the videos were relevant because of substantial similarity in the operative conduct (surreptitious, non-consensual genitalia-focused recording), and were admissible for at least two proper purposes:

  • Identity: enabling the jury to compare the camera-operator voice in the pool videos with Bycroft’s voice in the Peeping Tom videos, where her identity was independently established by visuals.
  • Absence of mistake or accident: rebutting anticipated claims that recording was inadvertent or that Bycroft did not knowingly participate in genitalia-focused filming.

The court declined to reach “common scheme or plan” because the evidence was admissible on the two grounds above, and any error on the third theory would be harmless.

III. Analysis

A. Precedents Cited

1. The governing admissibility framework: Huddleston v. United States

The panel anchored its analysis in Huddleston v. United States, which supplies the familiar four-part approach to Rule 404(b): (i) relevance, (ii) proper purpose, (iii) Rule 403 balancing (probative value not substantially outweighed by unfair prejudice), and (iv) limiting instruction if requested. The Bycroft panel focused on the two prongs the appellant contested—relevance and proper purpose—while treating the district court’s decision as compliant with the overall Huddleston structure.

2. Deferential review and “abuse of discretion”: United States v. Iverson and Gilbert v. Cosco, Inc.

Relying on United States v. Iverson, the panel reviewed evidentiary rulings for abuse of discretion, then used Gilbert v. Cosco, Inc. to define abuse of discretion as a “clear error of judgment” or exceeding permissible bounds. This mattered: by framing the inquiry as discretionary, the court signaled that reasonable trial-level judgments about similarity and purpose would be upheld.

3. Similarity as the “lynchpin” of Rule 404(b) relevance: United States v. Henthorn and United States v. Zamora

The opinion’s relevance holding is driven by the Tenth Circuit’s articulation that “similarity” is the “lynchpin” of Huddleston relevance, citing United States v. Henthorn. From United States v. Zamora, the panel drew two key propositions:

  • Acts need not be identical—only similar.
  • Similarity can be shown via physical similarity or a shared state of mind (i.e., the same kind of illicit objective or method).

The panel also invoked Zamora to address temporal proximity, noting that even larger time gaps have been tolerated (with Henthorn collecting cases). A two-to-three-year separation between pool and Peeping Tom videos did not defeat relevance.

4. Identifying the “significant characteristic”: United States v. Beechum

To answer the defense claim that child-victim footage is categorically different from adult-victim voyeurism, the panel relied on the idea that the “significant” shared trait controls the similarity inquiry, citing United States v. Beechum. The court identified that shared trait as: surreptitious recording of unwitting females’ genitalia. Differences (age of subjects; whether clothing was moved) were treated as circumstantial variations in means, not differences in the operative objective.

5. Identity under Rule 404(b) is not limited to “signature” modus operandi: United States v. Mares and United States v. Kimball

A particularly clarifying part of the opinion is its rejection of the defendant’s narrow view that 404(b) identity evidence must show a “signature quality” (modus operandi). The panel cited United States v. Mares for the proposition that a signature quality is only one way to prove identity. The court then invoked United States v. Kimball as an example of identity proof through more direct connections.

Applying that principle, the court held that the Peeping Tom videos functioned as identity evidence because they offered a reliable “bridge”: Bycroft’s voice in those videos was anchored to her visually identifiable body/face/tattoo/ring, allowing the jury to compare that voice to the voice in the pool videos. This is a practical holding: when the disputed identity feature in the charged act is a voice (or other sensory marker), other-acts recordings can be admissible to authenticate or connect that marker, even absent “signature” uniqueness.

6. “Excising” other-acts evidence: United States v. Kelley and United States v. Lucero

The defense argued the district court should have redacted the Peeping Tom videos to show only enough to identify Bycroft. The panel addressed this with United States v. Kelley, which recognizes a “duty to excise” uncharged-wrongs material where it can be done “without destroying” the relevance of what remains, quoting United States v. Lucero.

The court found no abuse of discretion because (i) the defense did not request excision at trial, (ii) excision is discretionary, and (iii) the district court already limited the government to three videos while permitting them to be played in full. Notably, the panel added a functional justification: for the absence-of-mistake theory, the “uncharged wrongs” component (the up-skirt recording attempt) is what makes the clips probative; heavy redaction would “nullify the very purpose” of admission.

7. Absence of mistake and “disparate circumstances”: United States v. Commanche

The defense relied on United States v. Commanche to argue that disparate circumstances undermine the use of other acts to show absence of mistake. The panel distinguished the Commanche hypothetical (slapping vs. murdering with a car) as too disconnected to show intent without devolving into propensity. Here, the linkage was not general “bad character” but the specific recurring behavior of covert genitalia-focused filming, used to rebut claims of accidental recording or lack of knowledge about the filming’s nature.

B. Legal Reasoning

1. Relevance through similarity: focusing on conduct, not victim category

The court’s relevancy reasoning turns on a careful reframing of what “fact of consequence” the other acts made more probable. The defense wanted the court to compare (adult voyeurism) vs. (child pornography production) as distinct moral/legal categories. The panel instead compared the concrete conduct at issue: operating a camera to capture unsuspecting females’ genitalia without consent. On that view, the acts share:

  • Objective: genitalia-focused sexualized recording.
  • Method: surreptitious filming adapted to circumstances (moving clothing when feasible; positioning the camera when direct filming would be detected).
  • Participants: Bycroft and Jason acting together in both sets of recordings (as the evidence suggested).

The court treated the age of the recorded person and the specific mechanics of exposure as situational differences rather than disqualifying dissimilarities. This approach effectively limits the relevance inquiry to whether the prior act meaningfully increases the probability that Bycroft was the operator in the charged videos.

2. Proper purposes: identity and absence of mistake/accident

Identity. The opinion’s key move is recognizing that the Peeping Tom videos are not introduced to show “she is the kind of person who makes illicit videos” (propensity), but to provide a reliable exemplar of her voice tied to her confirmed identity. Because the contested question was whether the voice in the pool videos was hers, the other acts served as comparative evidence with an independent basis for identification (visible features).

Absence of mistake/accident. The court accepted that Bycroft could suggest innocent explanations: that recording was inadvertent, or she did not know the nature of what was being captured. The Peeping Tom videos, including Bycroft’s initial claim that her phone “spontaneously” recorded, made it more likely that such an explanation was not true in the pool-video context. This is classic Rule 404(b)(2): using prior intentional conduct to rebut “it was an accident” defenses, so long as the inference runs through intent/knowledge rather than character.

3. Trial-management discretion: limiting the number of videos rather than micro-redaction

The opinion implicitly approves a pragmatic trial-management technique: limiting volume (three videos rather than five to ten) as a means of reducing prejudice while preserving probative force. It also reinforces that appellate courts will rarely second-guess how a district court calibrates presentation (full clips vs. partial clips) absent a timely and specific redaction request and a clear showing that probative value could be preserved without the prejudicial portions.

C. Impact

1. A usable pathway for “identity-by-voice” Rule 404(b) evidence

The decision provides a clear doctrinal pathway for admitting other-acts recordings where: (i) the charged conduct includes an unidentified speaker/operator, and (ii) the other acts include the same voice coupled with independently identifying visuals. Future prosecutions may cite United States v. Bycroft to argue that identity can be proved by comparative sensory evidence, not just by “signature” modus operandi.

2. Similarity is functional: “means” can vary with circumstance

By accepting that different settings require different techniques (moving clothing vs. camera placement), the opinion strengthens a functional understanding of similarity: courts may focus on the illicit aim and adaptive method rather than demanding near-identity in mechanics. That can broaden the admissibility of Rule 404(b) evidence in technology-facilitated sexual-privacy violations where tactics vary across environments.

3. Limits and cautions

  • The opinion does not eliminate Rule 403 concerns; it simply holds there was no abuse of discretion on the record presented. Future litigants should still anticipate careful balancing given the inherently inflammatory nature of voyeurism and child-sexual-exploitation evidence.
  • The court’s discussion of excision suggests that defendants should make timely, specific redaction requests if they want narrower presentation; failure to do so may weaken appellate arguments.
  • Because the panel did not reach “common scheme or plan,” the case’s strongest precedential value lies in identity and absence-of-mistake rationales.

IV. Complex Concepts Simplified

1. What is Rule 404(b) evidence?

Rule 404(b) generally forbids using a person’s prior bad acts to argue “she did it before, so she probably did it again” (propensity). But it allows prior acts for specific, non-character reasons—like proving identity, intent, knowledge, or absence of accident.

2. “Relevance” here means “similar enough to help decide a real issue”

The other act must make an important fact more or less likely. In this case, the important fact was who operated the camera in the pool videos. The other videos were relevant because they showed Bycroft operating a camera in a similar kind of illicit recording situation and captured her voice.

3. “Identity” does not always mean “signature” crime patterns

Sometimes identity is shown by a distinctive method (modus operandi). But it can also be shown more directly—for example, by linking a voice to a known person through video where the person is visibly identifiable, and then comparing that voice to the unknown voice in the charged recording.

4. “Absence of mistake or accident”

If a defendant suggests the charged act happened by accident (e.g., “my phone recorded on its own”), prior intentional recordings can be used to show it was likely deliberate rather than accidental—so long as the jury is asked to draw the inference about intent/knowledge, not “bad character.”

V. Conclusion

United States v. Bycroft reinforces a practical Rule 404(b) principle: when the contested issue is the defendant’s identity as a camera operator (including voice identification) and when the defense may suggest accidental recording, prior illicit recordings can be admitted if they are substantially similar in the conduct that matters and are offered for proper purposes like identity and absence of mistake. The opinion also clarifies that “identity” under Rule 404(b) is not confined to “signature” modus operandi evidence; direct comparative evidence such as voice matched to independently identifying visuals can suffice, subject to the trial court’s discretion and the usual safeguards.