A serial killer is an individual who murders a series of victims over a period of time, typically with gaps between each killing. Some serial killers kidnap and/or torture their victims prior to murdering them. While it’s not always clear what motivates serial killers to commit such heinous acts, abnormal psychological processes—notably severe antisocial tendencies—are to blame. In society, serial killers often generate fascination along with fear; their crimes tend to bring notoriety, media attention, and “fans” who study their crimes or, in some cases, form relationships with the murderer.