BK fits the standard 'profile' of every nutcase serial killer. I personally find it offensive when people excuse the behavior of these perps by trying to use his 'being bullied, overweight, not socially included' as a reason why they do this.
Most people in life have been bullied, overweight, or socially excluded at some point in their lives. They do not go out and murder or mass murder because of it.
BK is obviously fairly intelligent, enough to be able to be starting his PhD studies in Criminology. He would have average or above reasoning skills and knowledge of right and wrong and the consequences of such. I personally think he planned to commit the 'perfect crime' because he thinks he's the smartest guy in the room, and because he hates everything E,X,M &K were.......which is everything he is NOT.
I'm not opposed to the seeking the DP in this case, but for some reason I think it would just continue to feed BK's ego. Maybe it would be better for him to have to live out his life day after day as just another convicted felon slogging through the penal system.