If we had a time machine, and could place 1,000 different babies with this dude's parents, each baby an exact physical twin of this dude, each one diagnosed with the same mental issues, and each one would grow up facing the exact same circumstances, upbringing, same incidents all throughout life, it is my contention that NONE of them would have committed this crime. All of these factors- mental illness, mistreatment by others, etc.- they all play a part- but none of them decides the issue, IMO. What made THIS guy commit this crime is that he chose to be evil.