Watched piers doing the psychopath programe. I just want to say that the person is telling the truth. He has all the hallmarks of autism, including the need for revenge, the feeling of being alone, when no one else can see it. That, now that he is older and has more control over his mind he would turn his feelings on his self. (ASD has very high risk of suicide in adults because, they have such difficulties with their feelings in what is a cruel world for them) His rigidity of mind and body is not abnormal in the aspie world, none of which excuses what he has done!! but does mean that with more investigation with autism specialists you may find out why he did what he did.
My adult son used to give back what he loved playing with the most to hurt his father or me, he never understood that he was hurting himself. He also talks without showing emotion, neuro typical people do not understand ASD/Asperger people at all. The person would not be the first of them to commit murder for what seem to be crazy reasons.