California investigators were able to track down “Golden State Killer” suspect Joseph James DeAngelo using a relative’s genetic information stored in genealogical website databases, the Sacramento district attorney’s office confirmed to HuffPost on Thursday.
Police arrested DeAngelo, a 72-year-old former police officer, Tuesday in connection with the so-called Golden State Killer series of murders ― as many as 12 homicides, 45 rapes and several burglaries that investigators have spent decades trying to solve.
Sacramento County District Attorney Anne Marie Schubert said at a Wednesday news conference that investigators found DNA evidence linking DeAngelo to two of the unsolved murder cases. Investigators believe those homicides are connected to at least 10 others committed by the same individual.
“We all knew that we were looking for a needle in a haystack, but we also all knew that the needle was there,” Schubert said.
Asked by reporters where officials had obtained DeAngelo’s DNA, Schubert would say only that they used a “discarded DNA sample.” More information, she said, would be forthcoming.
On Thursday, Chief Deputy District Attorney Steve Grippi confirmed reports that investigators used DNA collected from one of the crime scenes decades ago and compared it to genetic profiles on genealogical websites. Such sites allow individuals to present DNA samples in order to learn about their family backgrounds and determine any genetic predispositions they may have.
Grippi would not comment on which sites were used in the investigation. But one such service, called GEDmatch, said in a statement on Friday that its database was used in the investigators’ search.
“Although we were not approached by law enforcement or anyone else about this case or about the DNA, it has always been GEDmatch’s policy to inform users that the database could be used for other uses, as set forth in the Site Policy,” the company said in a statement shared with HuffPost.
The statement added that site users should “understand the possible uses of their DNA, including identification of relatives that have committed crimes or were victims of crimes.” Those concerned by such potential uses, it said, should not upload their DNA to the database and/or remove already uploaded DNA.
Other well-known genealogical websites 23andMe and Ancestry said they were not involved in the investigation.
“It’s our policy to resist law enforcement inquiries to protect customer privacy,” a spokesperson for 23andMe said in a statement to HuffPost. “23andMe has never given customer information to law enforcement officials. Our platform is only available to our customers, and does not support the comparison of genetic data processed by any third party to genetic profiles within our database.”
Ancestry said in a statement: “We have not been in contact with law enforcement regarding the Joseph James DeAngelo case. Ancestry advocates for its members’ privacy and will not share any information with law enforcement unless compelled to by valid legal process.”
After narrowing in on family trees that were potential matches, investigators focused their search on DeAngelo, who had lived in the areas of the attacks and fit the age profile.
The Sacramento County Sheriff’s Department then began watching DeAngelo and collected two DNA samples to cross-reference with the DNA from the crime scene, though officials did not elaborate on their methods for collecting those “discarded” samples.
Both results came back positive, leading to DeAngelo’s arrest Tuesday. He is scheduled for arraignment in Sacramento Superior Court on Friday.
This story has been updated with a statement from GEDmatch.
This article originally appeared on HuffPost.