JOHN DANKOSKY: I’m going to finish with a fascinating story. Remember last year’s arrest of the Golden State Killer? The case drew lots of attention for its clever use of consumer genetic testing websites to catch the killer, and for all the murky ethical questions that came with it. But it wasn’t the first time that law enforcement had used this technique to solve a cold case. 

Detectives looking for the Golden State Killer took their inspiration from an earlier case in New Hampshire, known as the Bear Brook murders. In that case, police were up against an unknown killer and unidentified victims until they relied on a genealogy database called GEDmatch to help them with a break in the case. It was a strategy that would change the game for forensic investigations in cold case murders, and it’s also the basis of an excellent new true crime podcast from New Hampshire Public Radio called, Bear Brook. 

With us now to talk about it is New Hampshire Public Radio reporter and host of the podcast, Jason Moon. Welcome to the show, Jason. 

JASON MOON: Hey, John. Happy to be here. 

JOHN DANKOSKY: Maybe you can just very quickly tell us about this story, because I know it’s a very convoluted story, but this case that you started following and some of the twists and turns that take us to the science. 

JASON MOON: Yeah. It is. It’s a very sprawling case that literally spans the country and more than three decades. But one way to get into it is to think about it as beginning with one missing persons case. So a woman of the name of Lisa, growing up in Southern California, thought for years that she had been abandoned by her father at a young age, but because of an unrelated murder case that happened while she was in her 20’s, she and police found out that person wasn’t actually her father. 

So you have a situation where she and police had a kidnapping case that was decades old, but now they had the questions of who was she, and where did she come from, and what was her real name, and who was her real family? And so the quest to answer those questions in a strange meandering way led all the way back to New Hampshire and to some other mysteries along the way. 

JOHN: I’m John Dankosky. This is Science Friday from WNYC Studios, and we’re talking with Jason Moon, the host of the Bear Brook Podcast. So Lisa, this missing person, suggested to law enforcement that they use genetic testing websites, the kind that anybody can use. Maybe you can explain the process though– the police go through for genetic testing and genealogy to identify someone. 

JASON MOON: Yes. So one thing that’s really important to understand is that if you have your DNA on say, ancestry.com or 23andMe, police don’t have access to that. They can’t just go and look around and try to find suspects. So what happened was there’s another website called, GEDmatch that is sort of a– it’s a non-profit– sort of built by two guys down in Florida who were just genealogy enthusiasts, and it allows for more sharing of the genetic information. 

And people will turn to GEDmatch to run more advanced searches on their DNA to look for distant cousins and the like, and also because it allows you to compare tests from the different companies. So if I tested on 23andMe and you, John, tested on ancestry.com, instead of one of us having to buy another kit and spit into a tube and wait a couple of weeks to get our results to compare each other, we could just take our data to GEDmatch. 

And this was a really powerful tool for genealogists who wanted to build family trees, but then people started using it on adoption searches finding out well, who were my adopted– my biological parents, if I was adopted. And then finally, it started to get used in law enforcement to find missing persons, which was what happened with Lisa. And then later, they started to identify suspects with this technique. And you know, the most famous of which being the Golden State Killer suspect. 

JOHN DANKOSKY: And as I suggested, what’s kind of creepy about this is if I put up my information, I’m really putting up information about my entire family– my entire family tree for law enforcement and everyone to search through. 

JASON MOON: Yeah. I mean, if you put your data in GEDmatch, that is certainly is a possibility. And it’s one of the things that’s so fascinating to me about this whole subject is that our genetic information is not only extremely personal about us and it has so much data that us, as individuals, and can be used to identify us, but it’s also this shared data set in a sense. 

Because in a way, that unlike fingerprints say, where each person has just an individual set of fingerprints and that’s that, with DNA, with the tests that they’ve developed over the last several years, your DNA is not only a marker that points to you, but it also points to your family that– and not just your immediate family, but up to fifth or sixth cousins and generation– hundreds of years back in time. So it really is a strange new space that we’re figuring out how to navigate. 

JOHN DANKOSKY: And people are navigating it who are amateurs. People who aren’t professional investigators, they helped to solve some of the big mysteries that you were looking at in this Bear Brook case, Jason. 

JASON MOON: That’s right. So these were these folks like Barbara Rae-Venter, who we talked to in the podcast. They got started doing these adoption searches where people wanted to find out who their biological dad was, who their biological mom was, and they would use genetic genealogy to find a distant cousin of the person who had contacted them. And then they would follow the family tree back to find out who their parent was. 

And then– now, they’re just using that same basic technique to find criminal suspects by taking DNA samples from crime scenes, finding a distant cousin of that crime scene sample, and then following the family trees and narrowing down to who could have possibly belonged to that DNA sample. 

JOHN DANKOSKY: There are so many twists and turns in this story. Jason Moon is a reporter for New Hampshire Public Radio, host of the excellent Bear Brook Podcast. And you can find out all about this. I would check it out anywhere you find your podcasts. Jason, thanks so much for joining us and congratulations on the work. 

JASON MOON: Thanks so much for having me.

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