Digital Forensics Experts, Rule 16 Disclosures, and Rule 414 Evidence from Unallocated Space: Commentary on United States v. Eby (6th Cir. 2025)

I. Introduction

In United States v. Richard Eby, No. 24-3716 (6th Cir. Dec. 19, 2025) (not recommended for publication), the Sixth Circuit addressed three recurring and practically important issues in federal criminal practice:

When and how a digital forensic agent’s testimony and work product constitute “expert testimony” under Federal Rule of Evidence 702, triggering detailed disclosure obligations under Federal Rule of Criminal Procedure 16(a)(1)(G).
How a trial court may properly answer a mid-deliberation jury question about whether specific images on the defendant’s computer depicted the charged minor victims, and how the invited-error doctrine constrains appellate review.
The admissibility, under Federal Rule of Evidence 414, of child sexual abuse images found in “unallocated space” on the defendant’s computer, and how Rule 403’s unfair-prejudice balancing applies to such evidence.

The defendant, Richard Eby, was charged in the Northern District of Ohio with conspiracy and substantive counts arising from his alleged participation in an online scheme, centered around the webcam platform “Chateen,” to lure underage girls into private chatrooms and coax or coerce them into engaging in sexual acts on camera. An FBI special agent, Adam Christensen, conducted an undercover investigation, captured IP addresses and usernames (including “perp6969” linked to Eby), and later performed a forensic analysis of Eby’s seized laptop using specialized tools (Internet Evidence Finder and Axiom).

A jury ultimately convicted Eby of:

Conspiracy to engage in sexual exploitation of children, 18 U.S.C. §§ 2251(a) and (e) (Count 1);
Conspiracy to receive visual depictions of minors engaged in sexually explicit conduct, 18 U.S.C. §§ 2252(a)(2) and (b)(1) (Count 3); and
Conspiracy to access with intent to view child pornography, 18 U.S.C. §§ 2252A(a)(5)(B) and (b)(2) (Count 4).

The jury acquitted him on the substantive sexual exploitation count (Count 2). The district court imposed a 390‑month prison sentence followed by ten years of supervised release.

On appeal, Eby argued three primary errors:

The government improperly presented Christensen as a quasi-lay witness, failed to comply with Rule 16(a)(1)(G), and sprung late-disclosed expert “reports” (Exhibits 62 and 63).
The district court’s answer to the jury’s question about whether images on Eby’s computer depicted the named minor victims both usurped the jury’s fact-finding role and shifted the burden of proof.
The district court improperly admitted evidence of 243 images of minors engaged in sexually explicit conduct found in Eby’s computer’s unallocated space, as “other acts of child molestation” under Rule 414, despite their allegedly overwhelming prejudice.

The Sixth Circuit (Judge Stranch, joined by Judges White and Murphy) rejected each claim and affirmed the conviction. While nonprecedential, the opinion offers a clear, detailed application of existing doctrine to modern digital‑forensics evidence and Rule 414 propensity evidence, and it underscores practical expectations for Rule 16 expert disclosures and handling of jury questions.

II. Summary of the Opinion

A. Expert Testimony and Rule 16 Disclosures

The court held that Special Agent Christensen’s testimony about his forensic analysis of Eby’s laptop was expert testimony within the meaning of Federal Rule of Evidence 702. Citing United States v. Ganier, 468 F.3d 920 (6th Cir. 2006), the court emphasized that interpreting forensic software outputs—such as identifying and reconstructing deleted files, analyzing browser artifacts, flash cookies, virtual private network (VPN) evidence, and anti‑forensics tools—requires specialized knowledge beyond a layperson’s abilities.

Turning to Rule 16(a)(1)(G), the court nonetheless concluded that:

The government’s written expert notice for Christensen complied with Rule 16, as amended in 2022, and
Even assuming arguendo some deficiency, Eby failed to show the requisite prejudice: he and his own expert had access to the underlying forensic “portable case file” (including Christensen’s tags and artifacts) approximately eleven months before trial. Any alleged surprise was not shown to have affected the verdict.

As to Exhibits 62 and 63—summary printouts of selected “tagged” artifacts exported from the Axiom portable case file and disclosed only on the first morning of trial—the Sixth Circuit agreed the government did not comply with the district court’s exhibit-disclosure deadline. Still, applying an abuse-of-discretion and prejudice standard, the panel held that:

The exhibits were not “expert reports” required to be disclosed under Rule 16(a)(1)(G), but rather trial summary exhibits of data already made available; and
Because the defense had full access to the underlying Axiom portable case file and tagged artifacts for nearly a year, Eby could not show that the late disclosure of the summary exhibits prejudiced his defense.

B. Response to Jury Question

During deliberations, the jury asked: “Were any of the images or videos found on Eby’s computer of the minor victims?” After argument, the district court chose an instruction that:

“There was no evidence on Eby's computer, Exhibits 44 and 51, that the images were or were not the minor victims.”

Defense counsel rejected the court’s initial proposal to tell the jury to rely on its recollection and instead preferred (though still objected to) the “no evidence either way” instruction. On appeal, Eby argued that the court should have instructed the jury to rely on its collective recollection.

The Sixth Circuit held that:

Any error was “invited error,” because defense counsel specifically rejected the “rely on your recollection” formulation the defendant now claims was required.
Under United States v. Barrow, 118 F.3d 482 (6th Cir. 1997), and United States v. Akridge, 62 F.4th 258 (6th Cir. 2023), a party generally may not appeal an error it invited, absent a showing of “manifest injustice,” which Eby did not even attempt to demonstrate.
Independently, the challenged instruction was substantively proper: it did not confuse or mislead the jury, did not comment on the weight of the evidence, and did not shift the burden of proof. It neutrally conveyed the state of the evidence and preserved the jury’s role as factfinder.

C. Admission of Rule 414 “Other Acts” Evidence

The district court admitted evidence that, in 2019, law enforcement recovered 243 images of minors engaged in sexually explicit conduct in the unallocated space of Eby’s computer. The court allowed the government to present a representative sample to the jury with a limiting instruction. Eby argued this evidence was unfairly prejudicial and attenuated from the charged conduct.

Applying Federal Rule of Evidence 414(a) (permitting admission of “other acts” of child molestation in a child-molestation prosecution) and Rule 403, the Sixth Circuit held:

The 2019 images qualified as “other acts of child molestation” under Rule 414(d)(2)(B) because they involved conduct prohibited by Chapter 110 of Title 18 (child pornography offenses).
The Rule 414 evidence was highly probative: it was close in time (three years apart) and similar in nature (self‑produced child pornography involving minors) to the charged conduct.
The fact that the images resided in “unallocated space” (deleted files recoverable only with forensic tools) went to weight, not admissibility.
Any danger of unfair prejudice did not substantially outweigh the evidence’s probative value, especially given the limiting instruction directing jurors not to convict Eby merely because he may have committed other wrongful acts.

Consistent with prior Sixth Circuit cases, the court also reaffirmed that Rule 414 contains no temporal limit; evidence of prior child-molestation acts many years old can still be admissible.

The panel therefore affirmed Eby’s convictions in all respects.

III. Detailed Analysis

A. Expert Testimony and Rule 16: Digital Forensics as Specialized Knowledge

1. Classification of Christensen’s Testimony as Expert Testimony

The government, in its Rule 16 notice, took the position that Christensen’s anticipated testimony “likely do[es] not qualify as expert or opinion testimony” and even argued on appeal that “the forensic software is the expert.” The Sixth Circuit explicitly rejected this framing.

Under Federal Rule of Evidence 702, an expert is someone whose “scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue.” The proponent must show it is more likely than not that the testimony:

Will assist the trier of fact;
Is based on sufficient facts or data;
Is the product of reliable principles and methods; and
Has been reliably applied to the facts.

In United States v. Ganier, 468 F.3d 920 (6th Cir. 2006), the Sixth Circuit previously held that an agent’s interpretation of computer forensic software results (such as running searches and generating usage reports) is expert testimony, because understanding what those reports mean requires specialized computer knowledge beyond that of an average juror.

The panel in Eby applies Ganier in a technologically updated context. Christensen:

Duplicated Eby’s hard drive and processed the image through forensic tools (IEF and Axiom);
Identified a range of artifacts (files, browser history, bookmarks, shortcuts, “LNK” files, flash cookies from Chateen, evidence of a VPN, and anti-forensics software);
Recovered deleted photographs and videos from unallocated space by “carv[ing] out the data and put[ting] it back together.”

Interpreting these recovered artifacts—especially reconstructing deleted files and inferring user activity from forensic traces—plainly entails specialized knowledge. The court therefore held that Christensen was an expert witness when he testified “about the forensic analysis of computers, media devices, and other items of electronic evidence.”

This is an important reaffirmation: digital forensic agents who explain how they extracted and interpreted forensic artifacts are not “just fact witnesses.” They must be treated, disclosed, and challenged as experts under Rule 702 and Rule 16.

2. Adequacy of Rule 16(a)(1)(G) Disclosures

Under Federal Rule of Criminal Procedure 16(a)(1)(G), when the government intends to use expert testimony in its case-in-chief and the defendant requests disclosure, it must provide a written summary describing:

The expert’s opinions;
The bases and reasons for those opinions;
The expert’s qualifications; and
A list of other cases in which the witness has testified as an expert in the past four years (per the 2022 amendment).

The advisory committee note to the 2022 amendment stresses that disclosures must be early and detailed enough to give the defendant a “fair opportunity” to meet the evidence, including by obtaining a counter-expert.

Eby argued that:

The government’s notice was too vague—containing only broad topic areas and lacking a complete statement of opinions and bases; and
The government falsely asserted he had already been given access to Christensen’s opinions and to the Axiom portable case file with the correct “tags,” but in his view he had not seen the files in the form or with the markings used at trial.

The Sixth Circuit rejected those arguments largely as factual and prejudice-based:

Defense expert Matthew Curtin admitted on cross-examination that he did have access to the Axiom portable case file, including Christensen’s tagged artifacts, during a multi‑day review at the FBI field office approximately eleven months before trial. He simply did not remember reviewing them or electing to copy them.
The drive Christensen prepared for Curtin included a “Portable Case File” folder containing all forensic portable case files from seized devices, including the Axiom portable case file with tags.
Christensen explained the structure and contents of this drive and indicated that portable case files (which excluded contraband imagery) could be taken out of the FBI office. Curtin did not take them but could have.

To obtain reversal for a Rule 16 violation, a defendant must show not just a technical error but substantial prejudice—typically, that he was genuinely surprised and that a fuller disclosure would likely have affected the outcome. See:

United States v. White, 492 F.3d 380, 404, 407 (6th Cir. 2007) (reversal only where Rule 16 violation causes substantial prejudice; defendant must show surprise and that outcome would differ with better notice);
United States v. Collins, 799 F.3d 554, 570 (6th Cir. 2015) (similar substantial-rights standard for evidentiary error);
United States v. Wells, 211 F.3d 988, 997 (6th Cir. 2000) (no reversal where defense had substantial pretrial access to content and bases of expert’s testimony).

The panel held that Eby could not meet this prejudice requirement:

The defense had extensive pretrial access to the underlying forensic data and tags that formed the basis for Christensen’s testimony.
Eby offered only a bare assertion of surprise, with no explanation of what he would have done differently with a more detailed notice or how the verdict would likely have changed.
To the extent there was any surprise, the court pointedly noted it stemmed more from the defense expert’s choices or memory than from government concealment.

As a result, the court “reject[ed] Eby’s claim of reversible error based on an allegedly deficient Rule 16 notice.”

3. Late Disclosure of Exhibits 62 and 63: Summary Exhibits, Not Expert Reports

Exhibits 62 and 63 were summary exhibits consisting of selected tagged artifacts exported from the Axiom portable case file—8 tags in one, 78 tags in the other. They illustrated child sexual abuse imagery and related forensic artifacts from Eby’s devices. The government conceded that these exhibits were not disclosed by the district court’s ordered deadline (12 days before trial) and may only have been shared on the first morning of trial.

Eby argued that:

These were expert reports that should have been disclosed under Rule 16; and
The late disclosure itself, in violation of the court’s scheduling order, warranted reversal.

The district court treated Exhibits 62 and 63 not as Rule 16 “expert reports,” but as trial exhibits summarizing information already contained in Christensen’s Axiom portable case file. The Sixth Circuit agreed:

These exhibits “contained summaries of raw information exported from Christensen’s Axiom portable case file”; they did not themselves constitute the expert’s opinion report.
Rule 16(a)(1)(G) was satisfied by the written summary and by the disclosure of the underlying forensic files on which the exhibits were based.
Though the government violated the court’s exhibit deadline, appellate review focuses on whether that violation prejudiced the defendant’s substantial rights.

Citing United States v. Peck, 62 F. App’x 561, 566 (6th Cir. 2003), where summary exhibits disclosed two days before trial were upheld because the defense already possessed the underlying records, the panel held there was no prejudice:

Eby had access to the full Axiom portable case file, including the tagged artifacts summarized in Exhibits 62 and 63, for approximately eleven months.
He offered no concrete explanation of what additional preparation he would have undertaken had he received these particular printouts earlier, or how that would likely have changed the outcome.

In short, the late appearance of these exhibits at trial was poor practice but not reversible error. The key theme is that access to the underlying data for a substantial period can mitigate—even cure—the prejudice from late summary or demonstrative exhibits that simply organize that data.

4. Practical Takeaways on Expert Disclosures

While Eby is not precedential, its reasoning delivers clear messages for practitioners:

Digital forensic agents are experts. If they explain what forensic tools did, how they interpreted artifacts, or how they reconstructed deleted material, treat them as Rule 702 experts. Efforts to label them “fact witnesses” to avoid Rule 16(a)(1)(G) and Daubert scrutiny are unlikely to be embraced by the Sixth Circuit.
Disclose not only high-level topics but also underlying data. Where the defense has full access to forensic case files (including tags and artifact lists) well before trial, the court is much less inclined to find prejudice even if the narrative summary or demonstrative charts arrive late.
Defense experts must diligently review provided data. An expert’s failure to review or retain a portable case file, when given an opportunity to do so, will not ordinarily transform an otherwise adequate disclosure into reversible error.

B. Response to Jury Question: Invited Error and Neutral Instructions

1. The Jury’s Question and the Defense’s Litigation Position

During deliberations, the jury asked whether any images or videos on Eby’s computer were of the named minor victims. Evidently, the trial evidence did not include definitive testimony on this point; faces were not visible, and neither party offered positive identification testimony.

The district court first proposed the usual, neutral formula: instruct the jury to rely on its recollection of the evidence. Defense counsel objected and asked instead for an instruction affirmatively stating that “there was no evidence that the images found on Mr. Eby’s computer were of the minor victims.” The government objected, arguing that such a statement would be an inappropriate factual characterization by the court.

The court then gave defense counsel a choice:

Tell the jury to rely on its own recollection; or
Tell the jury that “there was no evidence on Eby’s computer … that the images were or were not the minor victims.”

Defense counsel preferred the second option (though noting a continuing objection), and the court used it.

2. Invited Error Doctrine

On appeal, Eby argued the court should have taken the first option and directed the jury to its own recollection—a position directly at odds with his litigation stance at trial. Under the invited-error doctrine:

A party cannot ordinarily complain on appeal about an error that it induced, invited, or affirmatively requested. See United States v. Barrow, 118 F.3d 482, 490 (6th Cir. 1997).
The court will review an invited error only to prevent “manifest injustice,” which requires a specific showing that failing to correct the error would seriously undermine the fairness, integrity, or public reputation of the proceedings. See Akridge, 62 F.4th at 264.

The Sixth Circuit held that:

Eby’s own trial strategy invited the complained-of instruction; he twice rejected the “rely on your recollection” approach he now urges.
He did not even invoke “manifest injustice” in his appellate briefing, much less develop an argument that the instruction caused such injustice.
That failure is fatal to appellate review under the invited-error framework.

3. Substantive Validity of the Instruction

Even apart from invited error, the panel concluded the instruction was substantively unobjectionable. A district court’s response to a jury question is reviewed for abuse of discretion and will not be reversed unless, taken as a whole, it rendered the instructions confusing, misleading, or prejudicial. See:

United States v. Davis, 490 F.3d 541, 548 (6th Cir. 2007);
United States v. Moran, 771 F. App’x 594, 601 (6th Cir. 2019);
United States v. Fisher, 648 F.3d 442, 447 (6th Cir. 2011) (quoted by United States v. Maike, No. 22‑6114, 2025 WL 1770555 (6th Cir. June 26, 2025)).

Key points in the court’s reasoning:

The instruction accurately reflected the record: no witness testified that the recovered images were, or were not, the minor victims; faces were not visible, and no definitive identification was made.
The instruction expressly limited itself to images on Eby’s computer (Exhibits 44 and 51) and did not speak to other evidence.
The court aimed to “strike[] the even-handed balance” because the evidence simply did not permit a definitive judicial statement one way or the other.
A more one-sided instruction—such as affirmatively stating there was “no evidence” that the images were the victims (as defense originally requested)—would have risked invading the jury’s domain and favoring one party.

The court’s approach aligns with the Fifth Circuit’s acceptance of a similar instruction in United States v. Infante, 404 F.3d 376, 389 (5th Cir. 2005), where the trial court responded to a jury question with: “There is no evidence either way.” That language was held not to improperly comment on the evidence or shift burdens.

Importantly, the Eby panel rejected the claim that the instruction shifted the burden of proof. It did not tell jurors that Eby had to prove anything; it merely described the state of direct proof on one discrete factual question. The burden of proof remained on the government under the general instructions.

4. Implications

The treatment of this issue reinforces several practice points:

Counsel must be cautious when dictating the exact language of answers to jury questions; those trial choices can foreclose appellate review.
Courts may give neutral “no evidence either way” responses where the record contains no direct evidence on a specific factual question, particularly when more one-sided language would improperly signal how the jury should view the evidence.
Claiming that such an answer shifts the burden of proof is unlikely to succeed where the instruction merely comments on the presence or absence of specific testimony and the overall burden instructions remain correct.

C. Rule 414 “Other Acts” Evidence: Unallocated Space Child Pornography

1. Rule 414’s Scope and Purpose

Federal Rule of Evidence 414(a) provides that, in a case where the defendant is accused of child molestation, the court may admit evidence that the defendant committed any other act of child molestation, and the jury may consider it “on any matter to which it is relevant,” including propensity.

“Child molestation” under Rule 414(d)(2)(B) includes any conduct prohibited by Chapter 110 of Title 18—i.e., federal child pornography and sexual exploitation offenses. United States v. Libbey-Tipton, 948 F.3d 694, 701 (6th Cir. 2020). Rule 414 thus expressly creates a propensity exception to the usual Rule 404(b) bar on prior-bad-acts evidence offered to show character.

However, Rule 414 evidence remains subject to Rule 403. A court may still exclude it if its probative value is substantially outweighed by a risk of unfair prejudice, confusion, or other specified harms. The Sixth Circuit has emphasized:

The probative value inquiry considers how similar the prior acts are to the charged conduct, the temporal proximity, and whether less prejudicial means to prove the same point exist. See Libbey‑Tipton, 948 F.3d at 701–02.
The probative value should be analyzed separately from the government’s “need” for the evidence, though need can matter in some contexts.
Rule 414 deliberately contains no time limit on prior acts. See United States v. Underwood, 859 F.3d 386, 393 (6th Cir. 2017) (reviewing legislative history); United States v. Jones, 747 F. App’x 348, 357 (6th Cir. 2018).

2. The Nature of the “Other Acts” Evidence

In Eby, the Rule 414 evidence consisted of:

243 images depicting minors engaged in sexually explicit conduct found in 2019 on the unallocated space of Eby’s computer (i.e., deleted files that were not stored in active directories but remained recoverable using forensic tools).
A “representative sample” of these images was displayed to the jury with a limiting instruction.

The government argued—and the district court agreed—that these images reflected prior instances of Eby’s involvement in child pornography, similar in nature (self‑produced child sexual abuse material) to the conduct charged in the Chateen conspiracy.

3. Probative Value vs. Unfair Prejudice (Rule 403 Balancing)

Reviewing for abuse of discretion (see Ganier, 468 F.3d at 925; Fowler, 819 F.3d 298, 304 (6th Cir. 2016)), the Sixth Circuit affirmed the district court’s Rule 403 balancing:

Similarity: The court concluded that both the charged conduct and the 2019 images involved “self‑produced child pornography,” making them sufficiently similar to have high probative value regarding Eby’s sexual interest in minors and propensity to engage in child-exploitation activity. Total identity of circumstances is not required.
Temporal proximity: The three‑year gap between the charged conduct and the 2019 images is modest. The Sixth Circuit has upheld admission of Rule 414 evidence more than 20 years old. See Underwood, 859 F.3d at 393. Thus, the Rule 414 evidence was not temporally remote in any meaningful sense.
Unallocated space and knowledge: Eby argued that images recovered from unallocated space were too attenuated and that he may not have known they were present. The district court held—and the Sixth Circuit agreed—that such arguments go to weight, not admissibility. Whether Eby knowingly possessed or viewed the images was a question for the jury; the mere fact that high‑specialization tools were needed to recover them did not negate their status as prior acts of child molestation.
Limiting instruction: The court instructed the jury that it could not convict Eby simply because he may have committed other unlawful acts. Such an instruction is a recognized way to mitigate unfair prejudice. See United States v. Kniffley, 729 F. App’x 406, 415 (6th Cir. 2018).

In United States v. Hruby, 19 F.4th 963, 969 (6th Cir. 2021), the Sixth Circuit held that when prior acts are “sufficiently similar” to the charged conduct, the probative value of Rule 414 evidence outweighs its prejudicial effect. Eby follows this line: the panel accepted the district court’s assessment that the key similarity—self‑produced child sexual abuse images—is enough to render the evidence highly probative.

Because Rule 403 grants district courts “very broad discretion” in balancing probative value and prejudice (see Libbey‑Tipton, 948 F.3d at 705), the Sixth Circuit saw no “definite and firm conviction” of error (Fowler, 819 F.3d at 304).

4. Significance for Digital Evidence and Rule 414

The case confirms several important points for the intersection of digital forensics and Rule 414:

Unallocated-space images can qualify as “acts of child molestation.” Even if the files are deleted and inaccessible to ordinary users, their forensic recovery can constitute evidence that the defendant previously downloaded, stored, or created child sexual abuse material—conduct falling comfortably within Chapter 110 and Rule 414(d)(2)(B).
Knowledge and intent are matters for the jury. Questions about whether the defendant knew the images were present or could access them do not bar admission; they instead go to the jury’s assessment of what inferences to draw.
Rule 414’s absence of a time limit has real bite. A three‑year gap is easily tolerated, especially where conduct is similar. Courts may admit much older digital evidence if it meets Rule 414’s substantive definition and passes Rule 403 balancing.

IV. Precedents and Their Influence

A. Forensic Testimony and Rule 16: Ganier, White, Wells, Peck

United States v. Ganier, 468 F.3d 920 (6th Cir. 2006) – Established that interpreting and presenting results from forensic computer searches is expert testimony, requiring Rule 702 qualification and Rule 16 disclosure. Eby applies Ganier squarely to modern tools (Axiom, IEF).
United States v. White, 492 F.3d 380 (6th Cir. 2007) – Articulated the prejudice standard for Rule 16 violations: reversal requires a showing of surprise and that the outcome would likely have been different with proper disclosure. Eby uses White to reject Eby’s prejudice arguments.
United States v. Wells, 211 F.3d 988 (6th Cir. 2000) – Even assuming deficient notice, no reversal where the “content and basis” of the expert testimony were already extensively discussed pretrial and defendant could not show a different outcome. Eby follows this reasoning, emphasizing extensive pretrial access to the forensic data.
United States v. Peck, 62 F. App’x 561 (6th Cir. 2003) – Approved late-disclosed summary exhibits where the defense already possessed the underlying information. Eby extends this logic to digital summary exhibits derived from forensic case files.

B. Jury Questions and Invited Error: Barrow, Akridge, Moran, Infante

United States v. Barrow, 118 F.3d 482 (6th Cir. 1997) – Classic articulation of the invited-error rule: a party cannot complain about an error it induced. Eby relies on Barrow to bar review of the instruction Eby helped craft.
United States v. Akridge, 62 F.4th 258 (6th Cir. 2023) – Clarified that invited error can be reviewed only for “manifest injustice,” which must be meaningfully argued. Eby’s failure to invoke or argue manifest injustice undercuts his appellate claim.
United States v. Moran, 771 F. App’x 594 (6th Cir. 2019) & United States v. Fisher, 648 F.3d 442 (6th Cir. 2011) – Provide the standard for reviewing responses to jury questions: instructions, as a whole, must not be confusing, misleading, or prejudicial.
United States v. Infante, 404 F.3d 376 (5th Cir. 2005) – Approved a neutral “no evidence either way” response to a jury inquiry. Eby echoes and invokes this reasoning in concluding that the district court’s response did not favor either side or shift the burden of proof.

C. Rule 414 and Rule 403: Libbey‑Tipton, Seymour, Hruby, Jones, Underwood, Kniffley

United States v. Libbey-Tipton, 948 F.3d 694 (6th Cir. 2020) – Defined child molestation broadly as any conduct prohibited under Chapter 110 and outlined the factors relevant to Rule 403 analysis of Rule 414 evidence. Eby applies this framework to unallocated-space images.
United States v. Seymour, 468 F.3d 378 (6th Cir. 2006) – Emphasized that although prior bad acts are usually inadmissible to show propensity, Rule 414 provides a specific exception in child-molestation cases.
United States v. Hruby, 19 F.4th 963 (6th Cir. 2021) – Held that where prior acts are “sufficiently similar” to the charged conduct, Rule 414’s probative value is not outweighed by prejudice. Eby invokes this principle to uphold admission of the 2019 images.
United States v. Underwood, 859 F.3d 386 (6th Cir. 2017) & United States v. Jones, 747 F. App’x 348 (6th Cir. 2018) – Confirmed that Rule 414 imposes no temporal restriction. Eby uses these cases to dismiss arguments about the three-year time gap.
United States v. Kniffley, 729 F. App’x 406 (6th Cir. 2018) – Recognized limiting instructions as a key tool to mitigate prejudice from Rule 414 evidence. Eby follows that approach.

V. Complex Concepts Simplified

1. “Unallocated Space” on a Computer

When a user “deletes” a file, it is not immediately erased from the disk. Instead, the operating system marks that space as available for reuse. Until new data overwrites it, remnants of the file remain on the disk in what forensic examiners call “unallocated space.”

Forensic tools like Axiom can scan unallocated space, identify fragments of deleted files, and reconstruct (“carve”) them into viewable images or videos. Ordinary users cannot see or open these files directly through the operating system, but their prior existence can be reconstructed and documented.

In Eby, law enforcement found 243 child sexual abuse images in unallocated space—meaning they had existed and been deleted. Whether Eby knew they were there or could access them again was part of the factual dispute, but their presence was treated as evidence of prior child-pornography possession and production.

2. Axiom and Internet Evidence Finder (IEF)

Axiom and Internet Evidence Finder (IEF) are commercial digital forensics programs that:

Ingest a forensic copy of a hard drive or device;
Automatically search for a wide range of artifacts (browser history, chat logs, cookies, deleted files, etc.);
Recover deleted material from unallocated space; and
Present the results in an interface where the examiner can “tag” items of interest for reporting.

The programs assist the examiner but do not replace expert judgment. The examiner decides which artifacts are relevant and how to interpret them. That interpretive step is what makes the examiner an expert witness under Rule 702.

3. Portable Case Files and “Tags”

A “portable case file” is a self-contained, exportable package generated by forensic software that:

Contains the results of the forensic examination (artifacts, recovered files, metadata);
Includes examiner-created “tags” marking particular items (e.g., images, videos, logs) as noteworthy; and
Can be shared with other examiners or counsel, often excluding contraband imagery or encrypting it to comply with legal restrictions.

In Eby, Christensen created such a portable case file and supplied it, with an explanation, to defense expert Curtin, who had an extended opportunity to review it and copy it. This undercut any claim that the defense lacked access to the basis of Christensen’s trial testimony.

4. Rule 16(a)(1)(G) Expert Disclosures

Rule 16(a)(1)(G) is designed to:

Prevent trial by ambush involving expert testimony;
Allow the opposing party time to retain and prepare a counter-expert; and
Help the court manage and gatekeep expert evidence under Rule 702 and Daubert.

The 2022 amendments require more than a vague topic list; they call for a summary of opinions, bases and reasons, qualifications, and a list of prior expert testimony. In Eby, the combination of the written summary and extensive access to the underlying forensic files was enough to satisfy the rule, especially given the lack of demonstrated prejudice.

5. Invited Error vs. Forfeiture

It is important to distinguish:

Forfeiture: A party simply fails to object or raise an issue. The appellate court may then review for “plain error.”
Invited error: A party actively solicits or endorses a particular action by the court and later complains about it. Appellate review is usually barred altogether unless “manifest injustice” is shown.

In Eby, defense counsel urged the court away from the “rely on your recollection” response and toward the “no evidence either way” formulation. That strategic choice triggered the invited-error doctrine, sharply limiting appellate review.

6. Rule 414 and Propensity Evidence

Normally, evidence of a defendant’s other bad acts cannot be used to show that he has a bad character and therefore probably committed the charged offense (Rule 404(b)(1)). But Rule 414 creates a specific exception for child-molestation cases:

Juries may hear about prior acts of child molestation and may consider such evidence as showing a propensity to commit similar acts.
The evidence must still pass Rule 403 balancing, which looks at cumulative impact, similarity, time gap, and the risk of unfair prejudice.

Eby illustrates how courts use similarity (self‑produced child pornography involving minors), relative temporal closeness (three years), and limiting instructions to justify admission of such evidence, even where the prior conduct is itself highly inflammatory.

VI. Impact and Broader Significance

A. For Digital Forensics Practice

Although unpublished, Eby reinforces that:

Digital forensic work that goes beyond rudimentary facts and into interpretation or reconstruction is expert testimony.
Government and defense alike should expect to treat forensic examiners as experts, satisfy Rule 16(a)(1)(G) fully, and be prepared for Daubert challenges where appropriate.
Making the full forensic case file available early—and documenting that defense experts had an opportunity to review and export it—substantially insulates convictions from later complaints of discovery ambush.

B. For Trial Management and Jury Instructions

Eby underscores:

Trial courts have considerable discretion in responding to jury questions, but must remain scrupulously neutral and avoid opining on disputed facts.
Neutral formulations that truthfully describe the state of the evidence (“no evidence either way”) are permissible and do not, without more, shift burdens.
Defense counsel’s tactical choices in shaping jury instructions can seriously limit the scope of appellate review through the invited-error doctrine.

C. For Rule 414 and Child-Pornography Prosecutions

The decision will likely be cited (even if only persuasively) for propositions that:

Prior child-pornography images recovered from unallocated space can be treated as child-molestation acts under Rule 414.
The probative value of such digital evidence, especially when it is similar in nature and relatively close in time to the charged conduct, can outweigh even substantial prejudice when accompanied by appropriate limiting instructions.
Rule 414’s lack of a temporal limitation continues to be operationalized in the digital age; data remnants from years earlier may still come into evidence.

VII. Conclusion

United States v. Eby offers a comprehensive, if nonprecedential, application of modern evidence rules to the realities of digital forensic investigations and child-exploitation prosecutions. The Sixth Circuit:

Clarified that forensic agents like Christensen are expert witnesses under Rule 702 when they interpret digital artifacts and reconstruct deleted data, thereby implicating Rule 16(a)(1)(G)’s disclosure requirements.
Emphasized that even if disclosure is imperfect, reversal requires a concrete showing of surprise and prejudice—something a defendant cannot establish if his own expert had extended access to the underlying forensic materials.
Reaffirmed the invited-error doctrine’s potency, especially in the delicate area of jury instructions, and validated neutral responses to jury questions that accurately reflect the record without usurping the jury’s role.
Confirmed that child-pornography images recovered from unallocated space may constitute “other acts of child molestation” under Rule 414 and that, when sufficiently similar and temporally proximate to the charged conduct, such evidence will often survive Rule 403 scrutiny, particularly with a limiting instruction.

For prosecutors, defenders, and trial judges in the Sixth Circuit and beyond, Eby serves as a detailed guide on handling digital forensic experts, structuring expert discovery, crafting responses to jury questions, and deploying or challenging Rule 414 evidence in technologically sophisticated child-exploitation cases.