Six years ago, a passing driver in Austin, Texas, found the body of a 28-year-old woman in a silver sedan. She had been sexually assaulted and strangled.

In June, a 911 caller reported finding a woman’s body in an abandoned home. The 34-year-old had also been sexually assaulted and strangled.

Now, police say, investigators believe one person killed both women.

Authorities are searching for the suspect in connection to a “series of murders” after DNA evidence linked the two killings to the same person.

Alyssa Ann Rivera was found dead on June 21 in an abandoned house, according to a news release from the Austin Police Department.

Surveillance video released by police shows a person of interest walking with Rivera shortly before she was murdered.

Police said it’s unknown how or when Rivera met the man.

The incident was initially believed to be an isolated event.

But on August 7, investigators found a DNA link between Rivera’s case and the unsolved murder from six years ago, police said during a news conference Thursday.

On April 14, 2018, the body of Alba Jenisse Aviles was found after she had left a nightclub, just over three miles from where Rivera was killed, according to the news release.

“There has been no suspect identified in either case,” it says. “However, the DNA evidence reveals the suspect to be the same in both cases.”

The DNA doesn’t match any records in the national database, police said.

Austin police Sgt. Nathan Sexton said it is “relatively rare” for someone committing “really violent murders” not to have been arrested or detained for a previous crime.

Police said there is no known link between the victims.

The investigation is ongoing as homicide detectives continue to search for leads.