LOUISVILLE, Ky. (WDRB) -- Two girls were killed on a northern Indiana trail in February 2017, and investigators hope the anniversary will bring someone who knows something forward.

Indiana State Police Superintendent Doug Carter told reporters Tuesday that he refuses to allow this case to go cold. Police have received thousands of tips, but nothing that can break the case wide open.

Abby Williams and Libby German were killed Feb. 13, 2017, in Delphi, Indiana. Police released a grainy photo of the suspect and audio of him saying "down the hill." 

Daniel Nations was brought to Indiana after failing to register as a sex offender in Johnson County. He was arrested last year in Colorado for allegedly threatening hikers with a hatchet. ISP detectives spoke to Nations about the deaths and said it no longer considers him a person of interest in the case.

Carter said Tuesday he believes the case is just one piece away from being solved. He also spoke directly to the killer.

"If you're watching this, and you're responsible, today may be your day," he said. "It might be tomorrow. But I can guarantee your day is coming. I hope that one day when we all meet Abby and Libby, that they tell us that you did well. That's my hope. We cannot allow evil to prevail."

The reward for information in the case remains at $240,000.

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