Before anyone comments further, please go read Lieutenant Colonel David Grossman "On the Psychology of Killing". He is a Professor of Psychology at West Point, and an Army Ranger.

What you hear of this incident will make perfect sense.

One key idea is "dehumanization", as exemplified by the quote "Fucking Coon".

Okay 2nd amendment people...how do you keep guns out of the hands of the Zimmermans of the world. Really. How?