Law enforcement agencies in Central Texas believe a serial killer is on the loose, after the slayings of two women in Austin and Bastrop County.

Until last week, officers believed the two incidents were unrelated because they occurred six years apart. However, after collecting and analyzing multiple sources of DNA from both crime scenes, they discovered that the DNA matched.

The Bastrop County sheriff’s office has been working with the Texas Rangers to identify the man’s DNA, though he does not match any records from the Combined DNA Index System, Austin Police Sgt. Nathan Sexton said in a news conference.

In response to a reporter’s question, he added that it is “relatively rare” for someone committing “really violent murders” not to have been arrested or detained for a previous crime, the Austin American-Statesman previously reported.

Here’s what we know.

More: Austin police request public assistance to identify local serial killer

Austin Police Department responded to scene of deceased woman in June

On June 21, officers with the Austin Police Department responded to a 911 call and discovered a deceased woman inside an abandoned home at 2600 Metcalfe Road.

The 34-year-old woman was identified as Alyssa Ann Rivera. Detectives determined she was strangled and had been sexually assaulted, Sexton said during the news conference. Surveillance footage showed she had been seen walking with a man shortly before she was killed, Guillen said. Police believe the man could be the person who killed Rivera.

Investigators believed Rivera’s murder was an isolated incident until Aug. 7, when DNA evidence from the scene where they found Rivera connected the unidentified man to the 2018 unsolved murder of 28-year-old Alba Jenisse Aviles in Bastrop County, Austin police Detective Christopher Anderson said.

Police declined to identify what DNA had been found, saying that multiple sources of DNA were found at both murder scenes.

The Austin Police Department and Bastrop County sheriff’s office have been collaborating on the cases since the link was determined, Sexton said.

Woman found dead inside parked vehicle in April 2018

Alba Jenisse Aviles, 28, was killed on April 14, 2018, after she left Club Caribe in Southeast Austin. Her body was found by a passing driver, who discovered Aviles inside her parked silver sedan in the 300 block of Old San Antonio Road, the American-Statesman reported.

Aviles was similarly sexually assaulted and strangled to death, Sexton said, adding that both scenes had a similar “modus operandi.”

Law enforcement do not believe the victims knew each other or were linked in any way, Sexton said.

More: How many bodies have been found in Austin’s Lady Bird Lake? Here’s what we know.

How to report information

Sexton encouraged anyone with information about either Aviles’ or Rivera’s murders to contact the Austin Police Department at 512-974-TIPS or submit anonymous tips through the Capital Area Crime Stoppers Program at austincrimestoppers.org or 512-472-8477.