A popular theory among criminal profilers is that serial killers can be divided into two types according to their crime scene evidence. The first type is organized and has a planful, thought-out approach to the crimes. These serial killers position the body, attempt to hide the body, tamper with the evidence, and take the weapon with them. Disorganized criminals are less careful and methodical. They use an improvised murder weapon, leave the body uncovered, leave a trail of clothing to the murder scene, and leave the victim’s belongings scattered about. The two types of serial killers are also assumed to use different modes of torture, rape, and murder.

Surprisingly, this theory has had little scientific evidence to back it up. In a 2004 article, David Canter and colleagues tested the organized/disorganized classification by studying the records of one hundred different serial killers. They found that all of the serial killers were predominantly organized in their approach. This makes perfect sense, given that serial killers are repeat murderers who manage to evade arrest for years. Disorganized features were less common, but present to some degree in almost all subjects.

The authors suggested a new way of classifying serial killers, dividing them into four new categories: those concerned with mutilation, execution, sexual control, or plunder. The first type mutilates the victim’s body, often after death. The second type executes their victims quickly after they are finished with them. The third type sexually tortures the victims while they are alive, presumably giving the killer a sense of complete control over another person. The fourth type ransacks and plunders the victims’ belongings.