Wait, How Did A Home DNA Kit Help Police Catch The Golden State Killer?

Photo: Justin Sullivan/Getty Images.
Yesterday, Sacramento police located and arrested Joseph James DeAngelo, the Golden State Killer (aka the East Area Rapist) suspect, who is believed to have committed more than 50 rapes and 12 murders over several decades.
This news came as a major shock to many people who had been mystified by the crimes for more than 40 years. Recently, the obsession has taken on a life of its own: Michelle Macnamara, comedian Patton Oswald's late wife, wrote a best-selling book about the Golden State Killer that was posthumously published in February, called I'll Be Gone In The Dark; and fans of the the true crime podcast My Favorite Murder will recall that the very first episode of the podcast covered these crimes, too. But, beyond the cultural fascination, the way that the police caught DeAngelo is also interesting because a home DNA kit was involved.
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According to The New York Times, investigators used DNA from the crime scene (which was collected in 1980) and entered it into a free online genealogy database, called GEDmatch, which provides "genealogical analysis tools for amateur and professional researchers and genealogists," according to the company's website. GEDmatch is not as user-friendly as, say, 23andMe or Ancestry, and its website is pretty bare bones (hey, it's a free service). But, in theory, anyone can upload their DNA and/or genealogical data using special software (called GEDCOM), and GEDmatch will provide DNA and genealogy tools for comparison and research purposes.
In this case, investigators received a lead about DeAngelo, and used GEDmatch to match his DNA with distant relatives, and eventually traced it right to his front door. One police officer who covered the crimes during the Golden State Killer's heyday told the Times that the process was "pretty complicated." But, given how readily available these types of tests are these days, how easy is it to pinpoint your distant relatives using DNA?
Genetic tests can tell you who has the same specific segments of DNA, or shares the same DNA variations, as you do, explains Carolyn Applegate, MGC, CGC, senior genetic counselor at Johns Hopkins University. "When we talk about doing genetic testing, what we’re typically doing is looking for areas of the DNA — that string or sequence of letters — where you are less common than the general population," she says. Based on how many of your variants match another person, you can determine how close of a relative you are.
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Some people have raised concerns about how ethical it is for a genealogy company to use people's DNA profiles to be searched against crime scene evidence. According to Applegate, these easy-to-use services have made genetic counselors very interested and concerned about the ethical, legal, and social issues related to genetic testing and healthcare. "It is a question of consent," she says. "If it is a publicly available database, did you then opt in for anyone who wants to use [your genetic profile] for whatever purpose they want to use it for?"
On the 23andMe website, the company has an extensive explanation about why 23andMe "unequivocally chooses to use all practical legal and administrative resources to resist requests from law enforcement." Similarly, Ancestry says their team reviews requests from law enforcement to make sure they meet legal requirements and their company policies. "If we believe a request is overly broad, we will try to narrow it to the extent legally permitted," Ancestry's website says. However, those are both paid services, so the companies are likely motivated to protect people's information, Applegate says. "But, at the same time, there's no guarantee of that," she says.
GEDmatch's policies seem to be a little looser. In a statement provided to Refinery29, Curtis Roger, the owner of GEDmatch, said that the company was never even approached by law enforcement about DeAngelo's case or the DNA. According to GEDmatch's site policy, Gedmatch is "unable to guarantee that users will not find other uses [for the data]" beyond research.
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"While the database was created for genealogical research, it is important that GEDmatch participants understand the possible uses of their DNA, including identification of relatives that have committed crimes or were victims of crimes," Roger's said in his statement. "If you are concerned about non-genealogical uses of your DNA, you should not upload your DNA to the database and/or you should remove DNA that has already been uploaded." If you have used GEDmatch and aren't down to share your information, the company recommends contacting them via email to have it removed.
So, while the Golden State Killer case may be officially cracked, there's no telling what other genetic information is out there that could be useful to law enforcement — or overzealous murderinos who have a background in genetics — in the future. The key thing to remember here is that, while it may be fun to send your spit to a company and find out quirky facts about your lineage, your DNA holds powerful information that could change your life, for better or worse.
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