Call them genetic detectives. They are sleuths who don’t carry a badge or gun.

They partner with police and crime labs to examine evidence-based DNA.

“We’re looking at genetic matches, building up the family trees and then building down to find the individual,” explains David Gurney, director of the Investigating Genetic Genealogy Center at Ramapo College in New Jersey.  “Using a combination of genetic information and traditional and genealogical methods.”

This next-gen forensic science, called investigating genetic genealogy, or IGG, helps track down criminal suspects through their own DNA.

“We take a DNA profile that’s been generated, in a case like this from a criminal case, and we will use that information to develop a genetic profile,” Gurney explains.

Among the cases the team is working on is the 1974 murders of Susan and Mary Raker, two sisters from St. Cloud who disappeared before their bodies were discovered in a quarry.

The killer has never been found.

Gurney says his team uses DNA collected from crime scenes to identify millions of genetic markers, and matches the profile through public ancestry sites GEDmatch and FamilyTreeDNA.  

“We usually get many, many matches, and we can use those different matches to identify common ancestors between them and common ancestors that lead down to the individual we’re trying to identify,” he notes.

Previously, law enforcement had to rely on CODIS, a U.S. Department of Justice database that has DNA samples from people arrested or convicted of violent crimes, which researchers call a ‘yes or no’ database.

“But with genetic genealogy, it’s more than a yes or no answer,” said Misty Gillis, an investigative genetic genealogist with Parabon Nanolabs, based in Northern Virginia. “It gives us plenty of leads and new information for the agency to work with.”

Gillis says Parabon has made 345 positive DNA identifications since 2018.

Despite the painstaking work, it’s not an exact science.

In one case, the team in New Jersey tracked down the genetic tree to three brothers, any of whom could have been the suspect.

“It’s then up to law enforcement,” Gurney says. “They have to go out and get a direct DNA sample from the individual that we have targeted to make sure that that lead is correct.”

Authorities say the success rate can vary.

Tracking those genetic trees can take as little as an hour or as long as many months.

It’s slow, exhaustive work that can take years, but researchers say the caseload numbers tell the story.  

“To me, it’s truly cutting edge,” Gillis says.  

“The IGG opened up two-and-a-half years ago, and we now have approximately ninety cases in our docket,” Gurney adds.