According to King, his own college writing would have certainly earned him a tag of "mentally ill." I'm not surprised, what little of him that I have read certainly put that thought in my mind. But trying to diagnosis the demons in the heart of an author through their writings and then holding them accountable to that diagnosis is a failing exersize that would stifle the creative process.
However, as King points out, there is a difference between being a writer and writing. To quote King's editorial:
Cho doesn't strike me as in the least creative, however. Dude was crazy. Dude was, in the memorable phrasing of Nikki Giovanni, ''just mean.'' Essentially there's no story here, except for a paranoid a--hole who went DEFCON-1. He may have been inspired by Columbine, but only because he was too dim to think up such a scenario on his own.
Well said from someone who ought to know.
On Predicting Violence