Can Ancestry Catch a Killer?

Golden State Killer

Decades after the Golden State Killer’s (also known as the East Area Rapist/Original Night Stalker) last attack, the cold case has finally been solved thanks to a website that any of us could and might already use—an ancestry site called GEDMatch. Uploading DNA found at the crime scenes, police were able to use the killer’s genealogy to track his family tree and narrow down likely suspects. Joseph James DeAngelo has finally been found out.

Cracking an infamous cold case might be a momentous occasion—one that’s been celebrated by everyone from the detectives involved to armchair detectives—but that hasn’t stopped people from moving on already and looking elsewhere, to other famous unsolved mysteries and cases that went cold years ago. Can our ancestry be used to catch other killers?

If Joseph James DeAngelo could be unmasked, why can’t the same websites be used to finally identify the Zodiac killer?

Case in point: the Zodiac killer. Zodiac operated in California in the late 1960s and early 70s and has been an open case with the California Department of Justice since 1969. Claiming to have killed 37 people, the serial killer is known to have murdered at least five people and injured two, although he could have as many as 28 total victims. A prolific letter-writer, he would also correspond with the press and police, writing mocking letters and ciphers that to this day have yet to be solved. The last letter arrived in 1974 and since then, there has been no (authenticated) contact with Zodiac, but, as the subject of endless books, films and TV shows, it’s a case that’s never fully left the public eye. With the arrest of the Golden State Killer, Zodiac is once again making headlines. If Joseph James DeAngelo could be unmasked, why can’t the same websites be used to finally identify the Zodiac killer?

It’s not just DeAngelo. This year, DNA has also been used to successfully identify two long-standing Jane and John Does: Lyle Stevik and Buckskin Girl, Marcia King.

The use of genealogy websites in the case is also a breakthrough. In the past, police were limited to using federal sites holding the DNA of convicted felons. Ancestry sites change all of that. Although the websites could be compelled to release their data to the police under a court order, there’s no need for them to do so and GEDMatch wasn’t contacted by law enforcement in the GSK case. Instead, investigators used the site like any other user uploading their DNA to identify relatives and trace their genealogy. The existence of such sites mean that in theory, the police have access to a much wider database that isn’t limited to convicted criminals.

When it comes to solving the Zodiac case, it might come down to the ciphers that allegedly concealed his identity, after all. The codes might not have been cracked, but he did leave DNA on the envelopes and stamps he used to send them. And as DNA forensic science didn’t exist at the time, current law enforcement have a significant advantage, even 50 years later.

Vallejo Police Department have already revealed they sent two of the envelopes for analysis that has only recently become available. A lot depends on whether they are able to get a full DNA profile from it. If they can, it can be uploaded to check for matches in the same way DeAngelo’s was.

So what are the chances it will work? It depends on the public and whether we use these websites. In order for there to be a match, a relative of Zodiac has to have uploaded their DNA to the site. There’s also no guarantee the evidence they have will elicit a full DNA profile—no awareness of DNA at the time of the crimes meant that investigators weren’t as careful with the evidence as they would otherwise have been. For now, we have to wait.

There might not be any guarantee that this will work for the Zodiac or that we will ever know who the killer really was. But there’s no changing the fact that the arrest of the Golden State Killer marks an important step for all cold cases, including the Zodiac. Now more than ever, the possibility of cracking cases that may have otherwise proved unsolvable feels very real: when, not if. If the Zodiac killer is still alive, he should be watching DeAngelo’s case very closely. He could be next.