Say I'm writing a novel about a murderer or killer of some kind. I'm curious as to what sot of things would compel or motivate a person to kill. Symptoms, things someone could notice before hand, that sort of thing. Perhaps a psychological condition that would render a person much more likely to commit murder, that sort of thing. Any direction for me? Thanks.
Try antisocial personality disorder. It's hallmarks are criminal/'sociopathic' tendencies. This disorder is largely found among criminals, and is more or less untreatable. Google it, there's some fascinating stuff on it.
At the risk of being cheesy, I would suggest probing the depths of your own mind. Searing jealousy.... blind RAGE. They are numerous motivations for killing - you don't have to be a psychopath to do it (at least I can imagine several different scenarios where someone normal crosses the line... then perhaps feels a horrific dread for what they've done? Or perhaps a dangerous/guilty high from exercising the ultimate power?) You have to find what sounds sincere to you....
Serial killers are exactly like drug users, they crave the sexual thrill of a kill just the same as a drug user craves his or her next fix. It's an addiction, which is assisted by a hatred and resentment of society and authority, as well as a hatred for those beneath him (which is everyone.) Often delusional but not often stupid, they seem so very normal, quiet and friendly, but are totally different people inside. That is my take on the mind of a killer. Like a rabid wolf in sheep's clothing.
Stress. If a person is in a bad enough situation that could result in him/her losing everything, or thinking they could lose everything they may resort to murder. The more common response to extreme stress is heart problems, addiction, and suicide, but a small number of people will snap and kill the perceived source of hardship. Or will do so under the influence of alcohol or drugs.
Google anyone of these, or look them up in a good psychiatric book. Paranoid schizophrenia, psychotic tendencies brought on by anti-depressants (it happens more frequently then people believe), hallucinogens gone wrong, sleep walking (people have been known to walk around looking for strangers to have sex with, sleep walking could remotely lead to murder), dissociative disorders, multiple personalities, cult brainwashing (don't laugh it happens), and borderline personality disorder.
The movie "Mr. Brooks" took a different twist in the situation. It's in theatres, maybe that would give you ideas.
Max, excellent ideas there. haha. However, while I mean uncommon, I mean more psychological. (Haha... I don't even know if I know what I mean)
