As much as I would love to see John Karr be guilty of this, I don't think he is. But I never thought the Ramseys killed their daughter. I think Boulder messed up and had to point a finger to cover their butts.
I kinda wonder if maybe this guy is a material witness as opposed to the killer himself. He made the statement he was 'present' when the girl died. It would be much easier to get him back into this country if he were accused of murder instead of being a witness. Just a thought.