Insane people are insane and may not be totally responsible for their acts, yet be able to think of ways to create mayhem. In this case, I heard on the news that this guy has a long troubled history of irrational acts.
At Pima Community College, the police responded 5 times to calls regarding his behavior; he was rejected by the Army for unspecified reasons; others have noted (after the fact, of course) that he did not make sense when talking of asking questions. He also allegedly had a drug problem earlier.
Yet, no one did much to ascertain his real condition (just let him go away). He obtained a firearm (legally or illegally, from a dealer or private purchase? - yet to be publically known).
Unfortunately for us, there will probably be repercussions in the form of tighter gun control.
