M3:  "Seems to have had a strong 'entitlement' issue...where did he get it? Apparently no Father figures to emulate. "   i think these folks feel like they got the shorted somehow and now they are mad at the world and don't care a whit about another human being. 
  there's not a lot of them to study as they tend to end their own lives...the ones who do live like malvo and  john Muhammad are tight lipped. the ulterior motive was for muhammad to hide his ex wife's murder amongst the others. all those people that died in D.C. - they were just filler.
 the common factor is mental illness alright.