Serial killers as a whole can generally be split into two categories according to the level of organization evident in their methods.
Organized killers tend to be intelligent individuals who often lure their victims to secluded locations with a combination of trickery and charm. Ted Bundy, for example, would sometimes wrap his arm in a fake plaster cast and ask young females for assistance. Because he was considered charming and did not look like a deranged killer, plenty of women voluntarily went off with him. Once they were alone, he would hit them over the back of the head, take them somewhere more secluded, kill them, and rape their corpses.
Organized serial killers also tend to dispose of their victims' bodies in a way that hinders detection (e.g. burial) and have an above average understanding of forensic science and other investigative techniques. They usually appear fairly normal on the surface, and friends and family are often shocked when their true nature is revealed. They generally have no real difficulty as far as romantic relationships are concerned, and may even be married with kids (as was the case with the notorious BTK killer, Dennis Raider).
Disorganized serial killers, on the other hand, tend to be more impulsive. They are often found to be suffering from some form of mental illness (though this is not necessarily what causes them to kill - there may be other factors involved) and may be of below average intelligence. They rarely take any real care to hide the bodies and rarely use trickery or charm to put their victims at ease, preferring to attack in more of a 'blitz' fashion. They are less likely to be in a stable romantic relationship and are also less likely to talk to their victims. Jack the Ripper is generally considered to be a good example of a disorganized serial killer.
It should be noted that a large proportion of known serial killers exhibit characteristics of both the organized and disorganized types. Furthermore, it is possible for serial killers to become more disorganized as their compulsion to kill grows stronger, or in times of high stress.
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