I define them, often, as batsh#t crazy or maybe fkd in the head. I stay away from clinical definitions, most of the time. Some lawyers, judges and juries, have been known to accept mental illness criteria, that lets the batsh#t crazy off with just treatment, instead of deserved punishment. I believe in capital punishment for these crazy fks. That crazy never gets to be a danger to society again, and I do not care about age. It lets parents and family members know to watch their crazy fk kids and family members, if they do not wish to see them, also parted from the mortal coil, as the crazy fk killed others. I don't do or approve of doing crazy crap. I am old, and had good examples. I remember a gym teacher/coach, beating some kid's ass in front of the entire class with a 3/4 inch thick oak paddle, punctuating his sentences with ass pounding pain, yelling "You stipid lil shit! Your daddy shoulda beat your ass, every damned day. It was a lesson, not on to the perp, but to everybody that witnessed that ass beating. Nobody would ever get away with crazy crap in that man's presence. The kid had taken a dodge ball off the rack, intentionally throwing at a kid, about 15 feet up the peg board, hitting him in the head, knocking him off to land on the gym floor, breaking his arm. If you teach them not to do crazy crap when young, fearing punishment, maybe they won't do crazy crap as adults, even more dangerous or deadly. Accept no defense on mental or anything else. Of course they are crazy. Who cares. Punish for the act, for the good of all. But, that's just me.