DELPHI, Ind. (AP) — The grandparents of one of two teenage girls slain during a winter hiking trip say they still believe investigators will find the killer.

Fourteen-year-old Liberty German and 13-year-old Abigail Williams of Delphi vanished Feb. 13 along a trail near Delphi, about 60 miles northwest of Indianapolis. Their bodies were found the next day in a rugged, wooded area.

More than two months later, Liberty’s grandparents, Mike and Becky Patty, say they still have faith police will arrest whoever killed the Delphi teenagers.

Becky Patty tells WTHR-TV she doesn’t like to think about “the possibility of not ever knowing” who was the killer.

She says the couple is focusing on plans for a softball field and park honoring the girls, and that’s helping them heal.