As bad as this may be to say... let alone sad:

Welcome to the Human Race.

We don't need reason to kill one another, yet we do anyway.... it could be anything from not getting enough attention as a child, to a teacher that yelled at him in 2nd grade, to his wife leaving him for a transgender.... gods know what twists people's minds as such and makes them want to kill anyone, for any reason.

Personal opinion: Chemical imbalences can do crazy things to a person. I was perscribed Prozac for about a year before I took myself off of it... it was turning me into an angry, spiteful, disrespectful prick.... I guess I shouldn't complain though... at least I wasn't depressed right?