Counter to the public's thinking, the celebrities who attract the largest number of stalkers - and typically it's not "if" a celebrity has a stalker, it's "how many" - are neither the most glamorous nor obnoxious, but rather the ones who seem the sweetest and most wholesome. They appear approachable.
Killers seldom meet the legal standard for insanity, which is quite different from the way most people use the word every day. Killers may be disturbed, but that doesn't necessarily mean that they can't tell right from wrong or are compelled to maim or murder.
One of the few times I'm hit emotionally is when I listen to the tapes sadists make of torturing their victims. There the person is currently suffering, you can hear them suffer, and that calls out for an empathic response. But when they're dead, when they're no longer suffering, when it's over, it's hard to feel empathetic for the corpse.
I do think a lot of sexual violence stems from experiences in childhood or at puberty. Some people become sadistic after suffering early abuse at the hands of parents, relatives or friends. But for others, the seed is planted in the formative years by the conflation of images of violence with those of sexual arousal. Magazines, TV shows and, especially, slasher movies are masters at doing this.
Psychiatrists are usually very well imbued with the clinical role, where helping the sick person is the goal. And that's quite incompatible with the truthseeking role. That's probably true of the other fields, too, but maybe more so of the personalities that gravitate toward psychiatry. They tend to care about people and wish to be helpful.
One of the problems with studies that examine the effects of violent imagery is that they typically use mentally healthy psychology students. If you want to do a meaningful study, show movies like Body Double and Copycat to a group of sexual psychopaths the day before you release them.
You condition a vulnerable boy at puberty to become aroused by brutality. It's the violence, not the nudity. Frankly, I wouldn't mind if every teenage boy had a subscription to Playboy. They'd be looking at attractive naked female bodies while they masturbated, not eviscerated female bodies.