Who killed Amy Gellert?

One night in 1994, Bob and Bunny Lehton arrived home from church to find a masked intruder in their home, pacing back and forth, saying they were just there to rob them and was waiting for a lift. Despite all offers for him to take what he wished, the man refused to leave... until the couple's daughter Amy Gellert came home. Amy was brutally attacked and died from her wounds, with the perpetrator escaping on foot. He's never been found.