When the East Area Rapist broke into the home of his first victim in 1976, human DNA had not yet been sequenced. When he reemerged as the Original Night Stalker and began a spree of murders in 1979, the World Wide Web still did not exist. For decades, the Golden State Killer—as he is now best known—got away with it all.
Then DNA and the internet appear to have caught up. Reporting from The Sacramento Bee and Mercury News indicates that police arrested Joseph James DeAngelo based on DNA found at crime scenes that partially matched the DNA of a relative on the open-source genealogy website GEDmatch. Previous searches of law-enforcement DNA databases had turned up no matches.
This way of finding people by DNA is new to law enforcement, but it is not new to genealogists, who immediately recognized their methods in the police’s vague descriptions. And the revelation has landed like a bomb. It at once demonstrates the power of genetic genealogy research and exposes the many ethical and privacy issues: Did any of DeAngelo’s distant relatives...