The suspected “Golden State Killer” who murdered 12 people and raped 51 others between 1974 and 1986 was finally captured this week thanks to the online DNA database of a genealogy company. It’s the first known case of law enforcement successfully using a commercial database in this way, experts say.

The Sacramento County District Attorney’s Office confirmed on Thursday what was first reported by the Sacramento Bee: that investigators sent the killer’s decades-old DNA samples to a genetic genealogy company and then searched its databases for relatives with matching segments of DNA.

“They then followed clues to individuals in the family trees to determine whether they were potential suspects,” the Bee reported. Once they had identified Joseph James DeAngelo as a possibility, the investigators set up surveillance on his home and got a fresh sample of DNA “from something he discarded,” the paper said.

Although everyone can be happy about catching a serial killer, there’s potential for abuses if the technology is used in other ways, said genetic counselor Laura Hercher.

“It’s the killer app for this technology — the literal killer app,” Hercher, the director of student research at the Sarah Lawrence College graduate program in human genetics, told BuzzFeed News. “If people were using it to track immigrants, we’d be rightfully up in arms.”

The report did not say which genealogy company investigators used. 23andMe and Ancestry.com, which manage two of the world’s largest DNA databases, told BuzzFeed News they were not involved in the case.

“We have not been in contact with law enforcement regarding the Joseph James DeAngelo case,” an Ancestry spokesperson told BuzzFeed News by email. “Ancestry advocates for its members’ privacy and will not share any information with law enforcement unless compelled to by valid legal process.”

23andMe said it has never given customer information to law enforcement. “Broadly speaking, it’s our policy to resist law enforcement inquiries to protect customer privacy,” a 23andMe spokesperson told BuzzFeed News by email.

“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.”Another industry leader, Family Tree DNA, did not respond to questions about whether it was involved in the case. The Sacramento County DA declined to answer any questions about what samples were used or how the testing was carried out, other than confirming the Bee’s reporting.

These genetic testing services regularly perform a kind of genetic triangulation of people’s DNA to find near and distant relatives. The process works by identifying unique combinations of segments of DNA that run in families and matching them up to other people in the databases, which might contain millions of people.

In 2013, a research team showed they could locate 50 anonymous people based on a DNA sample by triangulating their unique genes against ones found in public DNA databases of genealogy enthusiasts trying to find distant relatives. Five years later, there are more such databases and many more genomes to map against.

Privacy advocates such as the Electronic Privacy Information Center have raised concerns that searches for criminals based on the DNA of relatives threatened Fourth Amendment rights against unreasonable searches. “As science reveals new ways in which DNA may be used, the potential for misuse by government entities increases the risk to individual privacy,” EPIC has argued.

However, the Supreme Court and Congress have steadily increased the reach of law enforcement into the use of genetic investigation, most notably with the 2013 Maryland v. King decision, holding that warrantless searches of DNA did not violate the Constitution.

Original source: https://www.buzzfeed.com/danvergano/serial-killer-dna-testing?utm_term=4ldqpia.