Whatever the shooter is, he's not mentally ill -- notwithstanding the media's constant efforts to profile the sniper as a crazy white militia man.
By its nature "mind" can't be ill; only the body can be ill. And no bodily illness causes one to become a professional sniper murderer.
The problem is spiritual, not mental. It's called sin. The murderer is evil. Not sick. He will be dealth with by an armed citizen or a policeman, not by a psychologist.
Either possibility sounds agreeable to me, but I would like the interrogators to turn him and his pallies (ahem) into useful information sources before they are "dealt with".