You can often tell who is kind of prone to wackadoo things.

This guy didn't just snap. He planned and went hunting for little kids.

If you listen to people, you can generally find out who is "off". I know of one individual in my area who is going to warrant further observation in the future.

And he's not the most socially awkward.

The problem is generally psychopathy/sociopathy, not autism.

Although, I talked to a teacher last night who watched an aggressive kid with autism get pepper sprayed.

So, there is some general association with autism and violence in the teacher community already. That's impulse control.

Killers with multiple weapons and a strategic plan for mass murder generally don't have a problem with impulse control.