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Turning unsearchable mixtures into actionable intelligence for reliable DNA evidence

Edward Schikel, MBA, Terrance Lewis, MA, Matthew Legler, BS, Mark Perlin, PhD, MD, PhD, "Turning unsearchable mixtures into actionable intelligence for reliable DNA evidence", American Academy of Forensic Sciences Annual Scientific Conference, New Orleans, LA, 12-Feb-2026.


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Abstract

Learning Overview: Attendees will learn how probabilistic genotyping (PG) using the TrueAllele Investigative Database (TAID) converts unsearchable DNA mixtures into actionable investigative leads for volume crime cases. They will gain insight into how combining rapid batch testing with automated TAID accelerates intelligence development and strengthens cross-jurisdictional linkages and bolsters court-ready casework. Finally, they will understand how early DNA identification using TAID can disrupt criminal trajectories before they escalate into more serious and violent offenses.

Impact Statement: This approach demonstrates that combining traditional batch (high-throughput) DNA processing with TrueAllele Investigative Database (TAID) probabilistic genotyping transform previously unsearchable mixtures into actionable intelligence, achieving faster turnaround times that accelerate case resolutions. By generating early, evidence-based investigative leads through TAID, this model supports timely interventions, disrupts escalating criminal behavior, and improves public safety at scale.

Volume crime (VC) such as burglary, gun possession, vehicle or other property theft is more common than violent offenses but less often detected. 25 years ago, the United Kingdom pioneered the application of high-speed low-cost DNA databases to VC, thereby increasing detection, interrupting criminal careers, and converting leads into evidence. Cybergenetics TrueAllele® software helped distinguish simple profiles from less interpretable mixtures.

Today in America, the private sector addresses VC through local DNA databases. BodeHITS™ high-throughput services offer investigators higher speed 30-day laboratory turnaround at lower cost than custom casework. However, the speed tradeoff deemphasizes DNA interpretation, leaving unsearchable mixtures that yield no information.

Cybergenetics invented TrueAllele probabilistic genotyping (PG) 25 years ago [1]. The technology uses Bayesian probability to mathematically separate genotypes from DNA mixture data, one for each contributor. Comparing inferred evidence or reference genotypes produces a likelihood ratio (LR) match statistic that measures DNA association strength [2].

The TrueAllele Investigative Database (TAID) integrates BodeHITS DNA item data with fully-automated computer-driven high-throughput mixture interpretation. All inferred genotypes are automatically uploaded to a DNA database that conducts ongoing LR-based matching [3]. TAID is ideally suited for VC. Accurate and informative DNA data interpretation overcomes "unsearchable" mixtures, while parallel computing provides fast results at low cost.

Crime investigators at Pennsylvania's Montgomery County District Attorney's Office use BodeHITS to solve property crime. They also use RapidHIT™ ID (Applied Biosystems™) to develop reference DNA profiles on-site. The investigators wanted to convert their many unsearchable mixtures into more investigative leads. The county began a pilot project with Cybergenetics to explore the use of TrueAllele automated genotyping and its LR-matching database with their BodeHIT system and RapidHIT instrument.

In this study, Cybergenetics examined 1,234 Montgomery BodeHIT evidence items collected over three years. The TAID match yield was 1.32 evidence-to-evidence matches per item. TAID found 98% of the Bode items had an expected LR value over a thousand, with 75% exceeding a million. 60% of the BodeHIT evidence items were not searchable; TAID matched 72% of those mixtures.

When Montgomery requests a VC case report, within days Cybergenetics converts the TAID hit into court-ready evidence. A TrueAllele analyst reruns the evidence data four times, duplicating two different contributor assumptions. They report genotype match averages.

TAID helps resolve weapons cases. Handgun evidence typically contains 4 to 6 contributors. Since TrueAllele reliably solves DNA mixtures containing up to 10 contributors [4], it is useful for these VC cases.

TAID's supplemental evidence information is aiding VC investigations. In one car theft, TAID expanded an initial BodeHIT suspect match to 6 additional crime scenes. The new match information can uncover criminal career progression – from property crime to gun possession to violent crime.

TAID suspect detection enables earlier intervention to divert criminals and improve public safety. Previously unsolved volume crimes are now leading to DNA-informed arrests and guilty pleas. Better forensic DNA science informs better criminal justice.

References

  1. Perlin, M.W., Szabady, B. Linear mixture analysis: a mathematical approach to resolving mixed DNA samples. Journal of Forensic Sciences, 46(6):1372-7, 2001.
  2. Perlin, M.W., Legler, M.M., Spencer, C.E., Smith, J.L., Allan, W.P., Belrose, J.L., Duceman, B.W. Validating TrueAllele® DNA mixture interpretation. Journal of Forensic Sciences, 56(6):1430-47, 2011.
  3. Oblock, J., Butt, N. "The use of a database feature in the TrueAllele® Casework system to cross-reference DNA cases", American Academy of Forensic Sciences 71st Annual Scientific Conference, Baltimore, MD, 2019.
  4. Bauer, D.W., Butt, N., Hornyak, J.M., and Perlin, M.W. Validating TrueAllele® interpretation of DNA mixtures containing up to ten unknown contributors. Journal of Forensic Sciences, 65(2):380-398, 2020.

Links


  • American Academy of Forensic Sciences 78th Annual Scientific Conference - Program
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