When Caleb "Kai" Lawrence McGillvary, the hitchhiker hero, was arrested yesterday for allegedly killing a man police believe he'd had a sexual romp with, some were stunned. How could someone who'd seemed as hippy-dippy harmless and heroic as McGillvary turn out to be a killer? Sadly, if a Facebook post on what appears to be McGillvary's account is to be believed, a tendency toward violence may have been bred into him via a torturous and traumatic childhood.