Pure speculation on my part, but looks American Indian to me.
If I'm right, wonder if he was spoon-fed racial grievance history in public school, and imagined himself taking "revenge" on white America?
Also wonder if he was was adopted. Again, pure speculation on my part.
I want to know what psychiatric diagnoses had been applied to him, what mind altering drugs he was taking (with a prescription), and at what age he began taking them.