Unless a condition is really, really directly predictive - I'd be very cautious about stigmatizing folks.
I was kind of hoping you would go that way. Something interesting about these (full medical term here) total whacked-out-psycho-bunny shooters is that nearly all of them said that they were planning on shooting people to somebody/ somebodys.
I'd say that is pretty predictive.
And yet the actions of the professionals and others on the balance did not approach anything even close to interventive, even when the shooter made clear threats and demonstrated method and intent.
I'd like to think that there is a whole ward full of crazies that were stopped and locked up and just a couple made it through the cracks but I have no way of knowing that.