I agree the situation is a lose-lose on all sides; however that's all I agree with per se. I read both responses to this post (including your other one), but I'm replying to this in general
I've spent several years in school studying neuroscience and psychology and my focus was on behavior and worked specifically in that field with kids for little over a year. That's not counting the time I spent working in the public school system and private group homes for the mentally ill.
Bottom line is that it's combination of everything: that's what I've taken away from my years of schooling and experience. Who knows if he was influenced in any way, shape or form by violence in the media, and I doubt we'll ever know; however, it's really not the cause for anything. The catalyst possibly, but nowhere near the cause. One has to look at the person's upbringing along with the biology of the person's brain. Sure there are chemical imbalances in the brain for some, but that's actually relatively more common than you think. In fact, you couple that with the person's upbringing (in general, the person's environment), and you get the personalities you do. He was in med school, had money and may have felt he had the power. Who knows if he had seen abuse as a child or perhaps even seen his father treat women poorly, or even his parents treat others different from them like trash. There's never a singular cause.
What people don't realize is that violence and sex are rooted in human behavior and one could even go as far as calling it instinct. It's instinct because evolution had us on the path of survival of the fittest. Reproduce as much as possible and kill those that prevent you from doing so. I am clearly over-generalizing here and even over-exaggerating, but my point is: violence and sex have been around since the beginning of human history. Just because it is presented in a different medium doesn't make it any worse per se, just different. Should a 10 year old be playing say, Call of Duty or Grand Theft Auto? It really depends, and that's where it goes back to upbringing. Just because the games look a lot more realistic, doesn't make it any worse than the games of the past even it was all more pixel-ish and such. Did playing Double Dragon make me more violent when I was growing up? Not at all because my upbringing told me, what I was doing was fake; however, consequences were a whole lot worse. Me killing somebody in a game is totally different than somebody killing somebody else in reality. It's just that many parents fail to make that distinction, thinking that the kids will figure it out. Stupid assumption on those parents' part, in my opinion.
Looking at upbringing like I mentioned prior, like I said, he could have been abused, witnessed abuse, could have seen his parents treat each other or others like trash, etc. So many little instances combine and mold who he became: one who treated women who were providers like scum or as if they were beneath him, not like normal human beings like he should have. His parents suffer for his actions, but who knows if they unconsciously have themselves to blame.
I could go on and on, but I just wanted to throw in my opinion into the pot. It's getting late and I have a movie to catch (second time seeing Inception, y'all should go see if you haven't).
Just my two cents...keep the change.