How genealogical investigators continue to solve cold cases


INDIANAPOLIS — When investigators announced on Tuesday they had identified the “I-65 Killer” after more than 30 years, they gave a lot of credit to relatively new technology called investigative genealogy.

That same technology was used most famously to track down the “Golden State Killer.” It was also used to find a serial rapist in Shelbyville who was sentenced to 650 years in prison last week.

“It was never an intelligence application per se it was more so finding family members because they were interested in connections,” Susan Walsh said. “When it came to the police side of things they found this was a good avenue or a good area to get into to try and unearth relationships that they didn’t know existed” 

Walsh is an associate professor at IUPUI in the Forensic Investigative Sciences Program and runs her own research lab.

In cold cases, investigators can turn to labs like Walsh’s to sequence samples of DNA that were collected during the initial processing of the crime scene.

Those samples are then run through online genealogical databases where they will attempt to find a relative of the suspect.

“It’s looking at what samples that individuals have freely put up on the website, on the databases that could be matched to this unknown sample,” Walsh said. “You could find anything from up to 50 percent if it’s a parent or child match, all the way down to 0.005% which would be let’s say a fourth cousin relative.”

Once the forensic experts find that relative, they will then have to explore that person’s family tree in order to find the relative that actually committed the crime.

Walsh said that’s where the real work comes in.

“Basically you have to figure out the connection. That was only one point in the whole family tree,” Walsh said. “It’s the intelligence, the police work afterwards and the genealogical experts that draw all these trees and then you start to get the police back into examining what’s a good match what fits with the records of the area and other intelligent information they have.”

Oftentimes, when genealogists find a fourth cousin of their suspect, it’s difficult to even know where to begin. That’s where Walsh’s area of expertise comes in.

She has been on the cutting edge of phenotyping which is where they use specific markers on a person’s DNA to determine certain features of a person’s appearance. The technology is relatively new but can be used to find a person’s eye color, hair color and certain other facial features.

“This is all research within the last 10 years we could never do this before and it all comes down to working with the police and intelligence and working with librarians, individuals that are professionals in records searching,” Walsh said. “It’s a combination of individuals to try to solve it together.”

The technologies used in criminal investigations have only continued to be more useful, especially in cold cases.

“Some investigator still has to have the ware with all to think ‘oh this may be related’ or somebody brings it to their intention to pull these old samples and test it using new technology,” former FBI agent Doug Kouns said.

Kouns said he believes we’ll continue to see cold cases being solved as this technology progresses.

“In the 20 years of my law-enforcement career how far we came during that time to where look what we’re doing now,” Kouns said. “You just have to think from now until the next 20 years what are we gonna be doing, I think it’s pretty exciting.”

Susan Walsh at IUPUI pointed out that the technology does have its flaws. For example, the genealogical databases still need to grow.

Walsh said the current databases have roughly 1.5 million samples in them. If that number reaches 3 million, nearly every person in the population would be able to find a relative.

“It’s going to happen more often,” Walsh said. “As I said, biology is not difficult we’re just generating a genotype across the genome. People do it every day.”

You can find more information on Walsh’s work here.