Everything seems to indicate that something caused the perp to lash out--if not a scream, then JBR's struggling. There's been other crimes where there's been strangulation, and a blow to the head---the blow to the head being the final act of violence...even a pedophile in Switzerland I believe that inserted foreign objects---he claimed it was because something the child did angered him. Based on what we know about the crime scene, the first part of the kidnapping was accomplished, but things seem to have unravelled in the basement.

I just can't imagine what type of person could do this type of brutality. In the end, the violence was directed at JBR---I don't think JR was even in the perp's mind at that point.