Three years after Libby German and Abby Williams were murdered, the families of the victims as well as the city of Delphi are working to come to terms with tragedy.

But without a killer in custody, many unanswered questions remain. The two biggest questions surrounding the murders are who did it and why?

Libby's grandfather says he is remaining hopeful that police will find the killer, and with signs asking for tips still posted around town, Delphi is hoping for justice for the two teen girls.

"Take a whole minute, that's 60 seconds out of your life, it's not that long, to really look at those pictures and listen to that audio and say, 'Do I know this person, have I seen this have I heard that?'” Mike Patty said.

Patty is Libby's grandfather, and three years after the murder of his granddaughter and Libby's friend Abby, the pain is still very real and no killer has been brought to justice.

"The fact is that there was two innocent girls murdered and the guy is still walking around. We don't have any answers. There's no resolution. So with that respect, no, it doesn't get any easier, you know. We live it every day,” Patty said.

In 2017, Libby and Abby were dropped off along the Monon High Bridge Trail. It was an unusually warm February day.

Three years later, the paths are covered in snow, and what should have been a relaxing walk turned into pure terror.

The two teens crossed paths with an unidentified man and suspected murderer captured in video taken from Libby's phone. Their bodies were found not far from the trail.

A snow-covered memorial sits at a sign along the trail. It was near those paths that Abby and Libby would draw their last breaths at the hands of a killer.

"I can't give up hope. What else is there? And the fact that I believe in our justice system, I believe in our law enforcement, I believe in our society, because if we give up and just let people get away with things like this, then what does our society become?" Patty said.

The city of Delphi also holding out hope for justice three years later with signs posted around town, hoping for a break in the case.

"Why did this happen? Why did you do this to these two innocent girls? What did they do to you? Or what triggered you to do such a thing? And to him, out there, specifically, [what] I would say is, be accountable for your actions, and to this day he is not,” Patty said.

As the investigation goes on and police process thousands of tips on the case, Libby's grandfather keeps hope alive for not only justice for those two girls but a reunion with his granddaughter on the other side.

"Someday I'll meet her again, you know, when the good Lord lets me through the gates, and I hope she's able to say, 'Thanks, grandpa, you did a good job,'" Patty said.

If you at home know anything about this case, you are urged to contact police. To provide tips, use these resources:

Email: abbyandlibbytip@cacoshrf.com

FBI Tip Line: 844-459-5786

Carroll County Sheriff: 765-564-2413

Indiana State Police: 800-382-7537