This may not be totally a crock. Blood was found at the scene, and Hering had a head injury 10 years ago that resulted in short term memory loss.
I wouldn't put total credence in Powers's "confession" either. We just don't know the entire story yet ...
It was so good of you to join in the search effort. And his parents were and are deserving of comfort. All is not lost.
Perhaps it will end well for this young Marine. It would be sad if he really did go awol.