CHICAGO (CBS) — A sexual assault suspect who killed himself during a standoff with police in central Indiana last month also has been considered a possible suspect in the murders of two teenage girls – Abby Williams and Libby German – In Delphi two years ago, although he hasn’t been officially linked to the case.

Paul Etter, 55, shot and killed himself on June 27, after a five-hour standoff with police in Boone County, Indiana.

Carroll County Sheriff Tobe Leazenby confirmed Etter, among others, is being investigated as a possible suspect in the kidnapping and murders of Abby Williams and Libby German in Delphi in 2017.

Abby, 13, and Libby, 14, disappeared while they were hiking on the Monon High Bridge Trail near Delphi on Feb. 13, 2017.

Their bodies were found a day later on Valentine’s Day in a wooded area a quarter-mile from an abandoned railroad bridge that’s part of a trail system where the teens had planned to go hiking during a day off from school.

Abigail Williams (left) and Liberty German (right) (Credit: Facebook)

There have been no arrests or charges in their deaths.

Etter is one of multiple suspects being investigated, according to Leazenby. Investigators received a tip about Etter in the Delphi murders, but it’s unclear if or when authorities would be able to determine if he’s the killer.

According to published reports, at the time Etter killed himself, he had been wanted in the kidnapping and sexual assault of a 26-year-old woman who pulled into his driveway on June 22 after she got a flat tire.

Authorities said Etter asked if she needed help, but she didn’t feel safe, and declined, then drove down the road. He allegedly followed her until she pulled into a friend’s driveway, where he abducted her.

Etter allegedly took her back to his family’s home, where he held her and sexually assaulted her before taking her back to her car.

Five days later, police spotted Etter driving a truck that had been reported stolen, and pulled him over. That prompted a five-hour standoff that ended with Etter’s suicide.

Authorities are now investigating whether Etter might have killed Abby Williams and Libby German in 2017.

Police have said Libby snapped a photo of the killer, and recorded his voice on her cell phone before she died. Authorities also have released a sketch of the suspect.

Sketch of suspect in murders of two Indiana teens. (Credit: FBI)

More than two years since their deaths, there have not been any arrests, but earlier this year authorities released a new sketch of the suspect. They also released a short video clip and a longer audio recording of the suspected killer captured on Libby’s cell phone.

The new sketch released on April 22 is significantly different than the one released two years ago.

Indiana State Police released a new sketch of the man suspected of killing two teenage girls, Libby German and Abby Williams, in Delphi in February 2017. (Source: Indiana State Police)

An old sketch of the suspect shows him wearing a hat, and with facial hair, but the new sketch shows him clean shaven, with no hat. The facial features — including the shape of his chin, eyes, and nose — also are much different in the new sketch, but police did not explain the changes.

Indiana State Police Supt. Douglas Carter has said he believes the girl’s killer is “hiding in plain sight.” He said police are looking for the driver of a vehicle abandoned on County Road 300 North next to the Hoosier Heartland Highway on the day the girls disappeared. The vehicle was parked at the old Child Protective Services/Department of Child Services/Welfare building in Delphi.

Carter said investigators believe the killer is 18 to 40 years old; and is either from Delphi, works there, or is a regular visitor.

Police also released a brief video clip of the suspect recorded on Libby’s phone, showing him walking down a railroad bridge, wearing a blue jacket, jeans, and a hat.

An audio recording from Libby’s phone also caught the man saying “guys, down the hill,” a slightly longer clip than the one released days after the girls’ deaths.

Anyone with information about the should send tips to abbyandlibbytip@cacoshrf.com; or call the FBI tip line at 844-459-5786, or Indiana State Police at 800-382-7537, or Carroll County Sheriff’s Department at 765-564-2413.