My hypothesis is he's had "intermittent/explosive rage" issues since childhood combined with a bit of "injustice collector" grudges. Factors that lend to this theory are possibly his far far from home catholic high school (was he kicked out of public schools, given this mandate by juvenile court judge, escape from local bad reputation, etc?), reports of his broodiness, inexcusable shortness with students' parents, persistent sour attitude once he knew he'd not be offered another year's contract, and bulging at the seams angry "death stare" at random unknown hikers in the state park that had caused him zero problems. My guess is he thought with school starting next week, he'd never be caught and he needed this *release* before beginning yet another school year wherein e knew from too many past experiences he'd have to "play nice" in order to last the school year. I wouldn't be surprised if his previous several "tours of duty" saw him commit clandestine acts of violent release just before school started, though hopefully w/o being outright murderous.