Saturday, August 22, 2020

How DNA Caught the Golden State Killer

 Zoë Sharp


Between 1973 and 1986, 13 murders, over 50 rapes, and more than 120 burglaries were committed all over California by the same man—Joseph James DeAngelo. During his extended crime spree, DeAngelo was known by a variety of nicknames, including the Visalia Ransacker, the East Area Rapist, the Original Night Stalker, and the Golden State Killer.


As the original name suggests, he began in Visalia, California in 1973 by breaking into houses and vandalising them during his robbery. DeAngelo tended to take small, personal items of low value rather than large amounts of cash or expensive objects, scattering female underwear about the place and even helping himself to food and drink. In 1975, he killed Claude Snelling.


During this time, DeAngelo was a serving police officer, having joined after an internship and going on to work on burglaries. In 1979, however, he was fired after being prosecuted for shoplifting. He had also fought in the Vietnam War and, at the time of his retirement in 2017, was a truck mechanic.

Joseph DeAngelo when he was part of the Exeter Police Department


Early in 2018, Detective Paul Holes and FBI lawyer Steve Kramer uploaded the unknown Golden State Killer’s DNA into the GEDmatch website. This free online database was founded in 2010 with the aim of helping amateur and professional researchers and genealogists, including adoptees searching for their birth parents. It compared autosomal DNA data files from different testing companies, allowing users to search for relatives who had submitted their DNA, and also became much frequented by law enforcement. (In May 2019, however, GEDmatch increased its privacy guidelines so that users had to opt-in to sharing their data with law enforcement.)


By running a search through GEDmatch’s more than one million profiles, a team of investigators and genealogists were able to identify between 10 and 20 people who shared distant relatives with the Golden Gate Killer. This may seem fortuitous, but if you are of European ancestry and live in the USA, there is currently a 60% chance that a third cousin or closer relation will be in the database already. And this is when GEDmatch encompasses only about 0.5% of the US adult population. Estimates are that, once the GEDmatch figure rises to 2%, the likelihood of finding a third-cousin-or-closer match for those of European descent will rise to 90%.


From this information, the investigative team constructed a giant family tree. By gradually eliminating suspects, they got down to just two. One was then cleared by a further DNA test, and that left only Joseph James DeAngelo.


DeAngelo was arrested in April 2018. The statute of limitations had passed on the rapes and burglaries, but he was eventually charged with 13 counts of murder and kidnapping. He pled guilty to avoid the death penalty and on August 21 2020 the trial judge handed down multiple life sentences without the possibility of parole.


Currently, legislators are looking at the rules surrounding the use by law enforcement of DNA provided to ancestry-type websites. There are arguments to be made for personal privacy versus justice. Nevertheless, as of December 2019, approximately 70 cold case arrests have been made using this method, as well as identifying 11 John and Jane Doe bodies in the USA. This included one case where both victim and perpetrator were identified via genealogical DNA—the murder by James Richard Curry of hiker Mary Silvani (for many years called simply the Washoe County Jane Doe)—nearly 40 years after the crime was committed.

This week’s Word of the Week is nemophilist, meaning someone who is inordinately fond of woods, forests, or woodland scenery and visits them often. The word comes from the Greek nemos, grove, and philos love or affection.


  1. These belated captures of serial offenders like DeAngelo and "Grim Sleeper" Lonnie Franklin, as well as the Innocence Project always make me wonder on the one hand how many undetected serial offenders are out there, and on the other, how many are in prison for crimes they didn't commit.

    1. Indeed, Kwei. Far harder to get such evidence looked at in this kind of detail if someone was already in prison for the crime.

  2. Fascinating post, Zoe. I wish I could believe such technical advances would act as a deterrent. The greater improvement I see is on the other side a the coin that Kwei raises: to exonerate those falsely convicted. No mean advancement when it comes to the quest for justice.

    1. Thanks, Annamaria. It's never a deterrent because killers like DeAngelo don't believe they're ever going to be caught, never mind convicted.

      And yes, as you and Kwei point out, using such advances to take another look at 'closed' cases might be very interesting. But, sadly, not in the interests of the authorities...

  3. Hmm, imagine an orange DA wig on your first photo of DeAngelo, who pray tell, does he look like?

    1. You might very well think that, Jeff, but I couldn't possibly comment...