Serial killers are people who commit a series of murders, usually more than 3 and on a period covering more than one month.
They don't kill for ideological purposes or for the lure of money. They rather kill to experience powerfulness and to take pleasure from having the superiority on someone else.

The term appeared in the 70's when the fear-inspiring Ted Bundy, an American mass murderer, was doing the headlines of many newspapers in the United States.
The majority of serial killers have been abused in their childhood. Many of them present similar traits of personality and are psychopathics.
Psychopathy is a personality disorder characterized by anti social behavior. Serial killers lack of guilt and empathy.

3 specific psychological profiles have been identified to categorize the types of serial killers: the organized type, the disorganized and the mixed.
The organized serial killer hits great IQ scores. He plans all his murders methodically and leaves nothing to chance: he lures his victims with sympathetic manners to trap them more easily. He keeps focused on the crime scene to leave no traces and has a knowledge of forensic sciences. He usually feels proud of his “feats” and follows carefully his crimes' reports on the news. The way he proceeds is always the same and he sort of “signs” the crime scene in a momentary mind-lapse.
The disorganized serial killer is not intelligent. He kills impulsively and doesn't move the bodies from the crime scene to an other place. He has no global view on his crimes and has no clue on how covering them.

Their motives are numerous: some think that God gave them a mission to conduct, or that a certain type of people (prostitutes, homosexuals..) should be eradicated for the world's sake.
Others seek for the thrill and the adrenaline rush they get from killing. These people often try to make the “perfect crime”.
Some want to satisfy a sexual urge or need to exert an extreme power on their victims.

The most famous serial killer is Jack the Ripper; a London inhabitant who killed a great number of prostitutes. He slit their throats, ripped them and removed their inner organs.
He addressed several notes (on walls..) to the police investigating on his murderers but was never caught. The mystery surrounding his identity still lies in London.