http://theconversation.com/deadly-combination-the-psychiatric-disorders-that-might-have-made-anders-breivik-into-a-mass-shooter-68035
Breivik's narcissistic personality disorder and Aspergers Syndrome/Autism Spectrum Disorder made him a dangerous ticking time bomb. Breivik just like various mass killers and violent criminals have similar personality traits that make them do the unthinkable. Autistics are incapable of feeling empathy and if they do not get their own way they act violently and aggressively.