I think one could say the same thing about hippies.  :-)

The real reason this guy, and others, slipped through the cracks is because people naturally WANT to believe that some "good" part of him would come through.  He wasn't likely psychotic but rather a psychopath, and they can be excellent at hiding their problems when necessary. 

I think further study will find there was more to the bullying angle than previously reported.  Not that it makes for a valid excuse, but . . .

I wasn't aggressively bullied while in school, but it amazed me both then and now how adults just seemed to allow it to happen.  Some even seemed to encourage the practice by actively looking the other way and/or expecting the bullied to use the situation to "get tougher."  Well, that doesn't work for those already prone to psychopathic or narcissistic tendencies.