Aug. 19 (UPI) -- A California man who investigators firmly believe was a serial killer has been convicted of raping and killing two young women before he disappeared for decades and was ultimately exposed by his DNA.
Vaultz was finally arrested in 2019 after police matched DNA left at the scenes to his family lineage through genealogical websites.
"Using the latest in technology and forensics, we were able to secure a conviction against someone who targeted young women," Los Angeles County District Attorney George Gascon said in a statement. "I hope that [this] guilty verdict provides some comfort to the victims' families who have waited more than three decades to see this result."
Vaultz has also been linked to a third woman who was killed in Ventura County in 1988.
The families of both women were in the courtroom as the verdict was read.
At trial, defense lawyers argued that Vaultz was guilty only of having consensual sex with the women, and that it was someone else who showed up later and killed them.
Prosecutors in the case scoff at that notion.
"To believe the defendant's story, you'd have to throw out all your common sense," Los Angeles County Deputy District Attorney Beth Silverman said during closing arguments, according to KNBC-TV.
"You'd have to believe this defendant is the most unlucky person on the planet, to have three women all turn up dead with the defendant's semen inside them."
Keough, 21, was found dead in Montclair, Calif., on July 16, 1981, and forensic evidence was collected -- but it would be a long time before DNA analysis evolved to the sophisticated level it's on today.
When police ran the killer's DNA through a national database, the results led them to the other women's case. Duggan, 22, was found dead in the trunk of a car in Burbank, Calif., on June 9, 1986.
Police also ran the crime scene DNA through a genealogical database to try to find some of the killer's relatives. Ultimately, Vaultz was arrested during a traffic stop almost three years ago.
Genealogical databases have recently helped detectives solve a number of cold murder cases -- including more than a dozen that were attributed to the Golden State Killer in 2018.
The third case that prosecutors said was linked to Vaultz's DNA involved a 25-year-old woman named Janna Rowe. Police say they later found Rowe's jewelry among the belongings of Vaultz's mother.
At his trial, Vaultz testified that he couldn't remember meeting the women after sexual encounters with hundreds of partners. He faces life in prison without parole at his sentencing on Sept. 19.