The Murder of Beverly Jarosz

"We're no nearer to a solution now than we were when the body was found. For all I know, we're farther away from one."Can any words be harder for a loved one to receive? No parent can conceive of finding that their sixteen year old daughter has been murdered. For two days Beverly Jarosz's parents, Thaddeus and Eleanor, along with her sister Carol, held out hope that there would be a quick solution to the crime.
Those forty-eight hours must have flashed around them; a whirl of anger, guilt, fear and horror. Each minute simultaneously lasting hours but disappearing as soon as it arrived. Then it became apparent, the trail was already going cold. It would reach freezing point in the coming weeks and has rarely given even a hint of a thaw in the fifty-six years that have since passed.  And the question still remains.
Who killed Beverly Jarosz?