I've given it lots of thought. Most people that going on killing sprees do themselves in afterwards. The fact that this shooter in particular did not kill himself is a good thing.. Not because he is alive, but because it gives justice the chance to decide his fate instead of himself.
Death sentence would be doing him a favour. Personally, I'd rather have him spend the rest of his life in prison being raped and beaten while the guards turn a blind eye to it, and then he can die in his cell when he's good and old.
What do you want to become of him?