More than 40 years after a series of murders began in southern California, prosecutors have convicted the perpetrator.

A Los Angeles court found Horace Van Vaultz guilty of raping and murdering college student Selena Keough in 1981 in Montclair, east of Los Angeles.

The jury also found it established that five years later the former soldier sexually assaulted and killed 22-year-old Mary Duggan in the neighboring San Fernando Valley.

Investigators got on Vaultz's trail three years ago when they found a match when they ran DNA from both crime scenes.

Genetic genealogy, which compares a suspect's DNA to that found on commercial genealogy platforms, eventually led officers to the serial killer via a relative.

Vaultz is the first suspect that Los Angeles authorities have been able to identify by matching a relative's genetic makeup, the district attorney said after Thursday's guilty verdict.

DNA traces convicted the perpetrator

With the support of the American federal police, the investigators had looked for his DNA traces in Vaultz' garbage after the comparison.

The genetic material matched traces that investigators found on the victims' bodies in 1981 and 1986.

According to prosecutors, forensic scientists found DNA in Duggan's mouth, vagina and anus, now 67.

Vaultz had left the body of the 22-year-old naked in the trunk of her car in a Burbank parking lot after the assault.

The body of 20-year-old Keough, whom the perpetrator had strangled and hidden under a bush, also showed Vaultz' genetic traces.

The former soldier explained his DNA on the victims during the trial with his lifestyle.

As a swinger, he had sex with many women, including Keough and Duggan.

After the consensual sex, Vaultz testified, they were apparently murdered by another man.

"To believe this defendant's story, you have to turn off your common sense," the assistant district attorney told the jury during closing arguments.

Prosecutors believe Vaultz raped and murdered other women in Southern California.

The former soldier, who has lived in Bakersfield for the past few years and was arrested at a traffic stop in Inglewood near Los Angeles in 2019, was charged with the 1986 murder of Janna Rowe in Ventura County.

However, since the public prosecutor's office could not prove that he committed the crime at the time, Vaultz was acquitted.

However, his DNA was later found on the body of the twenty-five-year-old.

When searching his home, investigators found photos of more than 20 other women.

The images were released to identify possible additional victims.