How Advanced DNA Phenotyping and Genealogy Help Solve Cold Cases — Parabon NanoLabs’ Role

How Advanced DNA Phenotyping and Genealogy Help Solve Cold Cases

Law enforcement tools that extend DNA analysis beyond traditional matching — including genetic phenotyping and investigative genealogy — have advanced considerably in the past decade. In the Lowcountry, investigators recently closed a roughly 40-year-old cold case with assistance from Parabon NanoLabs, a company that provides bioinformatic phenotyping and genealogy services to police agencies.

How Phenotyping Works

Parabon’s Director of Bioinformatics, Ellen Greytak, explains that the company builds predictive models from very large, well-characterized datasets. "We started with a very large data set, so thousands and thousands of people," she said. "These are research participants whose DNA we have along with information about their appearance — eye color, hair color, skin color, and 3D facial scans. From that, we can look at the DNA to understand what’s different in the DNA between these people."

The company’s models draw on roughly 850,000 genetic markers associated with traits such as eye and hair color, ancestry indicators and aspects of face shape. Those markers enable bioinformatic specialists to produce predictive facial composites that offer more descriptive leads than standard forensic DNA matching alone.

Limitations And Age Progression

Greytak notes that phenotyping is not perfectly precise because many features — including weight, certain effects of aging, and lifestyle-driven traits — are not strictly encoded in DNA. To help investigators, Parabon generates young-adult predictive composites and then passes them to a forensic artist for age progression. The artist, trained in traditional forensic techniques, applies methods similar to those used for aging photographs or witness-based sketches to show how a person might look years later.

Practical Uses In Investigations

Predictive composites are most often used to eliminate or reprioritize suspects. As Greytak put it, "The most important way to use them is to eliminate people — to say, ‘We’ve been looking for a Hispanic male for six years and now Parabon is telling us we should be looking for a white guy with blue eyes.’" Investigators can use the composites to revisit prior leads, re-interview witnesses, or shift the focus of an active probe.

Parabon also combines phenotyping with investigative genealogy. Genealogy can link unidentified DNA to relatives and help narrow the pool of possible identities for both victims and perpetrators, which can accelerate identification and arrests.

Technical Challenges

Older evidence presents particular challenges. DNA stored at room temperature for decades — sometimes 40 to 50 years — frequently degrades, reducing the quality and quantity of usable genetic data. Investigators must also contend with mixed-DNA samples that contain genetic material from two or more individuals, which complicates analysis.

Case Example

In the investigation of the 1987 Lowcountry murder of Margit Schuller, Parabon produced a predictive composite and an older-age rendering that helped detectives focus their inquiries, demonstrating how combined phenotyping and genealogy can produce actionable leads in long-cold cases.

Bottom Line: Advanced bioinformatics and genetic genealogy are emerging as valuable tools for both cold-case resolution and streamlining active investigations, but analysts must account for degraded evidence, mixed DNA, and the inherent limits of phenotype prediction.