California investigators tracked down the former policeman who they suspect is the Golden State Killer responsible for dozens of rapes and murders by comparing crime scene DNA to genetic information on genealogy websites, a prosecutor said on Thursday.

The suspect, former police officer Joseph James DeAngelo, 72, was arrested on Tuesday outside the Sacramento-area home where he has lived for at least two decades, not far from the first of eight murders he is charged with committing 40 years ago.

DeAngelo is suspected in a dozen slayings as well as 45 rapes and scores of home invasions in a crime spree that spanned 10 years and 10 California counties during the 1970s and 1980s.