“Preservation over Source-Code”: Fourth Circuit Restricts Appellate Review of Probabilistic Genotyping Challenges and Clarifies Indictment-Variance Doctrine

Introduction

United States v. Melissa Beasley (consolidated with United States v. Brandon D’Angelo Chavis), decided on 31 July 2025 by the U.S. Court of Appeals for the Fourth Circuit, addresses the scope of appellate review when defendants seek to exclude probabilistic DNA evidence generated by the TrueAllele software and contests an alleged variance between an indictment and the crimes proven at trial.

The appellants, Brandon Chavis and Melissa Beasley, were convicted in the Eastern District of Virginia for a series of armed robberies and related § 924(c) firearm counts. On appeal they raised:

• Whether expert testimony based on TrueAllele should have been excluded because the examiner had not inspected the software’s proprietary source code.
• Whether a variance between the superseding indictment (caption mentioning “attempted” robbery) and the jury verdict (only completed robberies) required reversal.
• Whether the evidence was sufficient to support the convictions.

Judge DeAndrea Gist Benjamin, writing for a unanimous panel (Chief Judge Diaz and Judge Wynn concurring), affirmed on all grounds, producing three notable takeaways:

1. An appellate challenge to expert DNA testimony premised on non-disclosure of proprietary source code is waived if that precise objection was not raised at the Daubert hearing or during trial.
2. No fatal variance exists where the body of a superseding indictment charges completed Hobbs Act robberies and the jury convicts on that same offense, even if the caption references “attempted” robbery.
3. Extensive circumstantial evidence—including cell-site records, digital photographs, distinctive clothing, and a redeemed stolen lottery ticket—easily satisfies Jackson v. Virginia’s sufficiency standard.

Summary of the Judgment

The court affirmed every conviction and rejected each appellant’s argument:

• Expert Testimony: Because Chavis failed to object at trial on the specific ground that the examiner had not reviewed TrueAllele’s source code, the panel declined to evaluate the reliability challenge, citing the well-established rule that issues not preserved below are ordinarily forfeited on appeal.
• Sufficiency of the Evidence: The panel catalogued an “immensely powerful” body of circumstantial proof—surveillance videos, cell-tower data, DNA statistics, eyewitness corroboration, and incriminating text messages—upholding the jury’s findings against both defendants.
• Variance Claim: The caption’s reference to “attempted” robbery did not alter the indictment’s elements; therefore, no constructive amendment occurred and no prejudice flowed to the defense.

Detailed Analysis

Precedents Cited and Their Influence

• Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993) – Provides the framework for admitting expert testimony. The court emphasized Daubert but stressed that objections must be contemporaneously raised to preserve appellate review.
• United States v. Maxton, 940 F.2d 103 (4th Cir. 1991) – Quoted for the principle that only “exceptional cases” allow consideration of issues not presented below.
• United States v. Zayyad, 741 F.3d 452 (4th Cir. 2014) – Reinforced the requirement that an objection on appeal must rest on the same grounds asserted at trial.
• Jackson v. Virginia, 443 U.S. 307 (1979) – Dictates the sufficiency-of-evidence standard applied to the voluminous circumstantial proof.
• United States v. Redd, 161 F.3d 793 (4th Cir. 1998) and United States v. Banks, 29 F.4th 168 (4th Cir. 2022) – Groundwork for harmless versus fatal variances between indictment and proof.

These authorities collectively framed the panel’s reasoning: preservation doctrine curtailed review of the DNA issue, while established variance jurisprudence disposed of the indictment claim.

Legal Reasoning

1. Preservation Doctrine over Source-Code Access
   The court held that a party must make a specific objection at the Daubert stage to preserve appellate review. Although counsel briefly elicited that the expert had not inspected the code, counsel never argued unreliability on that basis. Therefore, the appellate panel treated the issue as waived and, significantly, did not reach whether TrueAllele is reliable absent source-code disclosure. This implicitly signals that future litigants must raise source-code demands early and explicitly.
2. Variance Analysis
   The caption’s stray word “attempted” did not add a new element. The body of the indictment, the jury instructions, and the verdict form focused solely on completed Hobbs Act robberies. Because the defendants were tried and convicted on the same legal theory actually charged, no constructive amendment or prejudice occurred.
3. Sufficiency Review
   Applying Jackson, the court catalogued multiple strands of evidence—cell-site locations tracking the defendants’ phones exclusively to the robbery zones, surveillance showing the same distinctive Volvo and orange reflective vest, text messages coordinating movements, and Beasley’s redemption of a stolen lottery ticket—to conclude that “the evidence was crushing.” The panel underscored that circumstantial evidence can suffice and that the jury was entitled to reject innocent explanations.

Impact of the Judgment

The decision, though unpublished, carries practical implications:

• Probabilistic Genotyping Litigation: Defense teams challenging software such as TrueAllele or STRmix must raise source-code or algorithmic-bias objections explicitly in the district court, or risk forfeiture. The Fourth Circuit’s refusal to entertain an unpreserved source-code argument may reduce the likelihood of appellate relief on similar claims.
• Indictment Drafting & Caption Errors: Prosecutors and defense counsel can rely on this opinion for the proposition that technical miscues in the caption—so long as the charging paragraphs are accurate—will not ordinarily constitute a fatal variance.
• Use of Digital & Circumstantial Evidence: The panel’s detailed affirmation signals continued judicial comfort with cell-tower data, deleted-file recovery, and digital photo caches as probative circumstantial evidence of presence and intent.

Complex Concepts Simplified

• Probabilistic Genotyping (TrueAllele): A computerized method that runs thousands of statistical simulations to estimate the likelihood that a given DNA sample matches a particular person. The output is a “likelihood ratio”—e.g., “33 trillion times more likely to match Chavis than a random person.”
• Daubert Hearing: A pre-trial procedure where the judge acts as “gatekeeper,” determining whether an expert’s methodology is scientifically reliable and relevant to the facts.
• Constructive Amendment vs. Variance: A constructive amendment alters the indictment’s elements, violating the Fifth Amendment. A variance is any difference between indictment and proof. Only an amendment, or a variance that prejudices the defendant, warrants reversal.
• Cell-Site CDR (Call Detail Records): Metadata generated when a phone connects to a carrier’s cell tower, revealing approximate location at specific times. Consecutive records near robbery sites can place a user in the vicinity of crimes.

Conclusion

United States v. Melissa Beasley underscores a vital procedural lesson: appellate courts will not rescue unpreserved challenges to cutting-edge forensic evidence. Defense counsel must articulate source-code and algorithmic-transparency objections squarely in the district court if they intend to dispute probabilistic genotyping results. Simultaneously, the opinion confirms that caption discrepancies alone do not create a fatal variance where the indictment’s body, instructions, and verdict align. Finally, the case illustrates the potent synergy of digital forensics, surveillance footage, and traditional eyewitness testimony in modern robbery prosecutions.

Going forward, practitioners should treat this decision as a roadmap both for preserving forensic challenges and for evaluating whether minor drafting errors truly risk constructive amendment. The Fourth Circuit’s emphasis on meticulous issue preservation may significantly influence litigation strategies in complex criminal cases involving proprietary analytical software.