"this guy's turn to violence makes me suspect he had some serious issues driving him, possibly in the mental health realm"
You "suspect possible mental health issues"? Amigo, what further evidence could possibly be required?
When we define criminality as evidence of mental illness, all we’ve done is medicalize criminality — which if anything hinders our ability to recognize abnormalities of the mind which may or may not lead to criminality.
I actually have tons of experience with people who suffer mental health issues, including psychotic illness. One thing that experience gives me is to be cautious about making armchair diagnosis from afar.