We can group the motivations of serial killers into three main types, which each include some pathologies ranging from a killer to another.
The motivation that can be described as “psychotic”, often comes under psychoses, and also hallucinations. The killer says he is driven to kill by higher entities, including God or the Devil. They are often prey to schizophrenia, and pulse murders so often disorganized. As it was the case of David Berkowitz or even Richard Ramirez.
The “moralistic” killer generally don’t suffer from psychosis or hallucinations, but has a very high opinion of morality, of right and wrong. They often see themselves as sporting a mission to eliminate what they consider immoral. Generally, prostitutes, homosexuals, etc. The famous Jack the Ripper is the most telling example.
The serial killer that can be considered as “hedonist”gives a notion of
intense pleasure to his murders. Violence, murder and domination of the victim is then about sexuality and possession. The hedonistic killer is often highly organized and can be pathologicaly psychopathic. The most obvious examples are Dennis Rader and Ted Bundy.
There is no such thing as a good influence, Mr. Gray. All influence is immoral – immoral from the scientific point of view. Because to influence a person is to give him one’s own soul. He does not think his natural thoughts, or burn with his natural passions. His virtues are not real to him. His sins, if there are such things as sins, are borrowed. He becomes an echo of some one else’s music, an actor of a part that has not been written for him. The aim of life is self-development. To realize one’s nature perfectly – that is what each of us is here for. People are afraid of themselves, nowadays. They have forgotten the highest of all duties, the duty that one owes to one’s self.
Lord Henry, The Picture of Dorian Gray, Oscar Wilde