sad thing is, he'll be found not guilty by reason of mental defect.
Only reason to kill another human is to protect/defend your own life or in an act of war. Any other circumstances are straight up murder. A person would have to have some screws loose to perform an unjustified killing in the first place, which is why this whole reason of insanity argument is straight up bull crap.
I agree this will probably be depicted in a movie (with a disclaimer that it is fictional and not based on true events).
