Serial Killer Myth 1: They're Mentally Ill or Evil Geniuses
Serial killers are rarely insane or brilliant, just deadly.
Updated March 31, 2026 | Reviewed by Ekua Hagan
The sensationalized images of serial killers presented in both the news and entertainment media suggest that they either have a debilitating mental illness, such as psychosis , or they are brilliant but demented geniuses, like Hannibal Lecter in the iconic film, The Silence of the Lambs .
Neither of these two stereotypes is quite accurate. Instead, serial killers are much more likely to exhibit antisocial personality disorders , such as sociopathy or psychopathy, which are not considered to be mental illnesses by the American Psychiatric Association (APA).
The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders , DSM-5, released by the APA in 2013, lists both sociopathy and psychopathy under the heading of Antisocial Personality Disorders (ASPD). These disorders share many behavioral traits, which leads to confusion between them. Key traits that sociopaths and psychopaths share include:
Very few serial killers suffer from any mental illness to such a debilitating extent that they are considered to be insane by the criminal justice system (1). To be classified as legally insane, an individual must be unable to comprehend that an action is against the law at the exact moment the action is undertaken.
In other words, a serial killer must be unaware that murder is legally wrong while committing the act of murder to be legally insane. This legal categorization of insanity is so stringent and narrow that very few serial killers are actually included in it.
Psychopathic serial killers, such as Ted Bundy, John Wayne Gacy, and Dennis Rader (BTK), are entirely aware of the illegality of murder while they are in the process of killing their victims. Their understanding of right and wrong does nothing to impede their crimes, however, because psychopaths such as Bundy, Gacy, and Rader have an overwhelming desire and compulsion to kill that causes them to ignore the criminal law with impunity.
When they are apprehended, serial killers are rarely determined to be mentally incompetent to stand trial, and their lawyers rarely utilize an insanity defense on their behalf. Once again, this is due to the extremely narrow legal definition of insanity, which simply does not apply to most psychopathic killers.
Even David Berkowitz, the infamous “Son of Sam,” who told his captors tales of satanic rituals and demonic possession, was found to be competent to stand trial for his murders following his arrest in 1977.
Considerable mythology also surrounds the intelligence of serial killers (2). There is a popular culture stereotype that serial killers are cunning, criminal geniuses. This stereotype is heavily promoted by the entertainment media in television, books, and films.
In particular, Hollywood has established several brilliant homicidal maniacs, like John Doe in the acclaimed 1995 film, Se7en . John Doe personifies the stereotype of the evil genius serial killer who outsmarts law enforcement authorities, avoids justice, and succeeds in his diabolical plan.
The image of the evil genius serial killer is mostly a Hollywood invention. Real serial killers generally do not possess unique intellectual skills. The reality is that most serial killers who have had their IQ tested score between borderline and above average intelligence (3). This is very consistent with the general population.
Contrary to mythology, it is not high intelligence that makes serial killers successful. Instead, it is obsession, meticulous planning, and a cold-blooded, often psychopathic personality that enables serial killers to operate over long periods of time without detection.
(1) Morton, R.J. 2005. Serial Murder: Multi-Disciplinary Perspectives for Investigators. National Center for the Analysis of Violent Crime. Washington, D.C.: U.S. Department of Justice.
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Scott Bonn, Ph.D., is a criminologist, TV news commentator, and best-selling author of Why We Love Serial Killers: The Curious Appeal of the World's Savage Murderers.
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This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.