Honestly, it was kind of a tragic scenario. He wasn't a cold-hearted bastard like Bundy or Gacy, he actually showed some remorse for his actions. His upbringing did have a lot to do with it, too. A lost cause, unfortunately.
I read the first half of the manga, though admittedly I didn't really hold enough interest to sludge through Shippuden. Would I still be allowed to play?