I believe the last thing on a shooters mind is wow, I might get the death penalty for my actions....
Most of them off themselves before giving law enforcement or anyone else the chance to stop them with lethal force...
As a human being, I have a a hard time wrapping my head around that there would be people in society (other then the shooter(s) ) who would allow this to go on if they new it was going to happen. If there is, then they’d get a speedy trial and execution on the way to their jail cell..