Three years after the unsolved murders of two teen friends in Delphi, Indiana, the case is set to get a fresh look on the Investigation Discovery show, “In Pursuit with John Walsh.”

For the show’s season season finale, John Walsh’s son, Callahan Walsh, visits Delphi in hopes of uncovering more information about the case and keeping the girls in the forefront of people's minds.

Libby German,14, and Abby Williams, 13, were both killed after setting out for a walk along a trail on Feb. 13, 2017. The following day, after authorities and residents combed the area, their bodies were discovered near the scenic Monon High Bridge, an abandoned railroad bridge over Deer Creek in Carroll County, Indiana.

Police never shared details on how the teens died. In the time following the murders, police released audio from Libby's phone of the girls' suspected killer saying "down the hill," and a single image of the suspect, but he has never been captured.

“This is a double murder that really shocked the country. When you have victims who are young children, it really pulls at the heartstrings,” Callahan said. “However, with this case, we do have a lot of evidence, video, audio of the suspect taken by the victims themselves, which is very interesting, because even though we have that evidence, we still don't know who this individual is.”

In July 2017, authorities released a sketch of a man they called a suspect in the case. He was described as a white male between 5-foot-6 and 5-foot-10, who weighed 180 to 220 pounds, and who had reddish brown hair. His eye color was unknown.

In 2019, police released an entirely different sketch of a man as they said the case was taking a “new direction." They described the new man as between the ages 18 and 40, and added that they believed he is “hiding in plain sight.”

The team on “In Pursuit With John Walsh” is hoping the episode will uncover some new leads for the case. Callahan said whoever the murderer is, he believes the man was familiar with the trail where the girls were found.

“Well, I went to the crime scene and I traversed that bridge, that railroad trestle myself. It's treacherous. It's very high off the ground. There's no handrails, there's planks missing,” Callahan said. “That is something that an individual would need to have experienced crossing to get over. And that person who followed Abby and Libby across the bridge made it across with no problem. It makes me believe that that person knew that area well, that (they) knew that terrain, because it's very difficult terrain, and had experience in that area.”

Last month, Libby’s mother, Carrie Timmons, expressed she thought the case was at a standstill, even though police had said it was in no way a cold case.

"We're not getting anywhere," Carrie Timmons told Inside Edition. "Three years is too long.”

Callahan hopes that although the case has been highly publicized, the new episode will serve as a reminder to the public.

“I think it's just a matter of time. I think somebody will come forward… I believe somebody who knows who this individual is but possibly is holding back that information out of fear of this person. And so I think time weighs heavy on your conscience,” Callahan said.

"I think continue telling the story, keep hammering the public over the head with Abby and Libby's story, keep it alive. And I think somebody will make that right decision. They'll saddle up, they'll come forward and give us the information that we need.”

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