Serial killer

A serial killer is a person who kills three or more people in three or more separate events over a period of time including an "emotional cooling-off" period in between the homicides. citation needed] The cooling-off period may last days, weeks, months, or even years. Many serial killers suffer from Antisocial Personality Disorder and not psychosis, and thus appear to be quite normal and often even charming, a state of adaptation which Hervey Cleckley calls the "mask of sanity." There is sometimes a sexual element to the murders. The murders may have been completed/attempted in a similar fashion and the victims may have had something in common, for example occupation, race, sex, etc.

The term serial killer is widely believed to have been coined either by FBI agent Robert Ressler or by Dr. Robert D. Keppel in the 1970s (the credit for the term is disputed). Serial killer entered the popular vernacular in large part due to the well-publicized crimes of Ted Bundy and David Berkowitz in the middle years of that decade.