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SAN DIEGO, Calif. — In the name of solving cold cases, investigators now have a powerful tool that’s becoming more prominent, and it involves using names submitted to companies that most likely have the DNA of someone in your family.

“Genetic genealogy is the merging of two well-known and well-established areas of inquiry,” says Jeffrey Vandersip, senior crime and intelligence analyst for the San Diego County Sheriff’s Department.

Recently, a Winston-Salem man was arrested for a murder in Elizabeth City. Officials say the crime was solved five years after the murder by using genetic genealogy.

For Vandersip and cold-case homicide detectives at the San Diego County Sheriff’s Department, interest in genetic genealogy began when it was used to solve the Golden State Killer case.

“I reached out to the FBI, the actual investigators who did the Golden State Killer case,” San Diego County Sheriff Cold Case Detective Troy DuGal said.

DuGal then approached his supervisors, seeking permission to pursue genetic genealogy in-house at the department.

“We were successful on our first case and subsequently we’ve opened several more,” he said.

If the investigators have suspect DNA – or the DNA of an unidentified victim – they can go down the same path as citizens, by inputting the DNA into something called GedMatch.

“When you get an Ancestry kit, and you put your DNA in Ancestry, it doesn’t match to a family member that may have potentially used 23andMe,” Vandersip said. “But GedMatch allows this cross-pollination.”

The investigators also use a tool called DNA Painter.

The first case the investigators solved was that of a 29-year-old woman who’d been murdered and sexually assaulted in 1984. They were able to identify the suspect but discovered he had died in a vehicle crash four months after the murder.

“When we got to the end, and we got the suspect identified, and we got together, I was elated,” DuGal said. “Any time you can identify a suspect in a homicide case, that’s amazing.”

The first case took them about a year to solve. They’ve now cut that turnaround time to about a third of that.

“The matches are typically third cousins and out,” DuGal adds. “We have yet to succeed on loading a DNA profile and hitting really close.”

The investigators often have to contact other family members as they build out their family trees, asking them to input their DNA.

“We actually reach out to persons when we get down to the living because we start in the 1800s and we come down,” DuGal explains. “They’ll tell us what their living family tree is and what they remember about their immediate ancestors above them.”

To date, about 95 percent of the people they approach agree to participate.

The team has opened six cold cases, solved three, and say they are close to solving two more.

“What’s amazing about this particular case is the break that we got to sort of figure out the family lineage, that bit of information was a hundred years old,” Vandersip details.

Since the team does the genetic genealogy within the department, other departments often contact them for seminars and advice.

“Everybody is very excited about this,” Vandersip said. “I think, we’re not unique, but there aren’t a lot of law enforcement agencies that have done all of this work in-house.”

The investigators also say, even though some people believe they modify DNA samples, they never touch them, and frankly, wouldn’t know how to change them if they could.