DNA from a tissue left in a rubbish bin led authorities to arrest a former California police officer suspected of being the Golden State Killer, court documents show.
The documents released on Saturday (Friday local time) about the arrest of 72-year-old Joseph DeAngelo detail the case that Sacramento County sheriff’s investigators pieced together to obtain an arrest warrant in April.
DeAngelo is suspected of committing at least a dozen murders and about 50 rapes in the 1970s and 1980s, making it one of California’s most vexing cases.
The Los Angeles Times reported that detectives took DNA collected from a semen sample at one of the crime scenes and plugged it into several genealogy websites, managing to link it to a distant relative of DeAngelo’s.
Detectives told the Times that with that link established, they then focused on DeAngelo because of his “age, employment and that he lived close to where many of the crimes were committed”.
Once they had identified their suspect, they began surveillance on DeAngelo which led them to a shopping mall where they took a swab from a door handle used by the suspect.
They then got a second DNA sample from a tissue in DeAngelo’s rubbish bin outside his home which gave them a conclusive match and the key piece of evidence required to get an arrest warrant, the court documents detailed.
The investigation had baffled Californian authorities for 42 years and even included leads as far away as Australia.
DeAngelo, a police officer, was arrested in a dawn raid in California’s capital, Sacramento, on April 25, and charged with a string of horrifyingly violent crimes from Oakland, near San Francisco, to Orange County, south of Los Angeles.
He allegedly broke into homes, threatened his victims with guns or knives and allegedly committed 12 murders, 51 rapes and more than 100 burglaries.
Police have also accused DeAngelo of a 13th killing – the shooting death of Claude Snelling in 1975 in Visalia, halfway between Los Angeles and San Francisco.
The serial killer and rapist would wear a mask and during attacks where he confronted a husband and wife he sometimes tied the man up, put dishes on his back and raped the wife in another room.
If the dishes fell he would know the husband was attempting to escape.
The serial killer also allegedly would stay at the crime scene after committing the rape or murder, go to the victim’s kitchen and make himself a sandwich or other snack before leaving.
Authorities said they were unable to identify him until the major DNA breakthrough in mid April.
Before that DeAngelo name never came up in their four decade-long investigation.
“We all knew as part of this team that we were looking for a needle in a haystack,” Sacramento County District Attorney Anne Marie Schubert told reporters.
“But we also all knew the needle was there.”
There was renewed interest in the case when true-crime journalist Michelle McNamara’s book I’ll Be Gone in the Dark was released in February and topped The New York Times bestseller list.
Ms McNamara died in 2016, but her actor-comedian husband Patton Oswalt helped finish the book.
US authorities were so keen to catch the killer they investigated a theory he moved to Australia and committed rapes on young girls in Melbourne in the 1980s and 1990s.
That rapist earned an Australian moniker – Mr Cruel.
Victorian Police investigated the potential link between Mr Cruel and California’s Golden State Killer and ruled it out.