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Serial Killers

Learn more about the research topic of serial killers.


A serial killer is conventionally defined as a person who murders three or more people in a period of over a month, with a “cooling down” time between murders. For a serial killer, the murders must be separate events, which are most often driven by a psychological thrill or pleasure. Serial killers often lack empathy and guilt, and most often become egocentric individuals; these characteristics classify certain serial killers as psychopaths. Serial killers often employ a “mask of sanity” to hide their true psychopathic tendencies and appear normal, even charming.

Crime Museum

America's Serial Killers image from flickr.

Image Credit: flickr user Terror on Tape

One of the oldest questions in criminology – and, for that matter, philosophy, law, theology – is whether criminals are born or made. Are serial killers a product of nature (genetics) or nurture (environmental factors)?

Peter Vronsky is the author of Sons of Cain: A History of Serial Killers from Stone Age to the Present, a book that explores why some people become killers, and others don’t.The book explores how our understandings of serial killers – called “monsters” before the advent of modern psychology – have changed over time, and considers answers to a difficult question: what, exactly, “makes” a serial killer?

Many serial killers are survivors of early childhood trauma of some kind – physical or sexual abuse, family dysfunction, emotionally distant or absent parents. Trauma is the single recurring theme in the biographies of most killers As a consequence of this trauma, they suppress their emotional response. They never learn the appropriate responses to trauma, and never develop other emotions, which is why they find it difficult to empathize with others.

The Guardian

Research shows that certain genes can predispose people to violence. Many serial killers experience childhood trauma or early separation from their mothers. As a consequence of that trauma or separation, scientists believe, they learned to suppress empathy or suffered damage to the areas of the brain that control emotional impulses. Serial killers often are loners who fear all relationships and seek to control, to destroy other people to eliminate the possibility of another humiliating rejection. Those who've studied serial killers believe that many are at least partly motivated by the attention and fame that mass media can provide mass murderers.

The Week

Roughly one in every five to six serial killers are female. There are significant differences in their psychopathology from male killers.

Research on female serial killers is difficult because they are fewer and harder to catch. Female serial killers have less tendency to leave bodies behind. They are quiet killers; they have longer killing careers. They are much better at it.

There is a less sadistic tendency. They tend not to torture their victim and they are less interested in mutilation. But the motivation is similar – the need for control over their victim. It’s not sex, it’s control, though they may assert it through sexual acts.

The types of predation in which female serial killers engage are often an extension or perversion of gender roles. For example, the expectation that women are in nurturing roles, caring roles. You have a category of female serial killers with Munchausen Syndrome by Proxey – mothers killing children, nurses killing patients.

The Guardian


The four main types of serial killers based by the type of crime they commit are as follows: thrill seekers, mission-oriented, visionary killers, and power/control seekers. Thrill seekers are serial killers that see outsmarting the law as some sort of amusement.

There have been 220,000 unsolved murders in the U.S. since 1980. Are serial killers to blame? Here's everything you need to know: 

  • Since 1900, there have been 3,000 identified American serial killers who've collectively killed nearly 10,000;
  • About 32 percent of these killers did so for enjoyment (thrills, lust, and power); 30 percent for financial reward; 18 percent in anger; 6.3 percent to advance a criminal enterprise; and fewer than 1 percent because a cult put them up to it;
  • Their favorite murder weapon was a gun (42 percent), although 6 percent preferred poison and 2 percent axes
  • About 52 percent were white, 40 percent black, and 6.7 percent Hispanic;
  •  Men outnumber women by a factor of 10;
  • Samuel Little, a transient former boxer and career criminal serving time for two murders, was recently identified by the FBI as the most prolific serial killer in U.S. history, after he confessed to 93 killings between 1970 and 2005.

The Week

Biographies of Famous Killers 

Ted Bundy

A biography for Ted Bundy.

David Berkowitz (Son of Sam)

A biography for David Berkowitz.

Jeffrey Dahmer

A biography for Jeffrey Dahmer. 

Gary Ridgway (Green River Killer)

A biography for Gary Rigway, 

Charles Manson

A biography for Charles Manson. 

Dennis Rader (BTK Killer)

A biography for Dennis Rader. 

Aileen Wuornos

A biography for Aileen Wuronos. 

John Wayne Gacy (KIller Clown)

A biography for John Wayne Gacy. 

Jack the Ripper

A biography for Jack the Ripper.

Joel Rifkin

A biography for Joel Rifkin.


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Bureau of Justice Statistics

Collects, analyzes, publishes, and disseminates information on crime, criminal offenders, victims of crime, and the operation of justice system.

National Museum of Crime and Punishment

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Office for Victims of Crime

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U.S. Department of Justice - Federal Bureau of Investigation

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Mark Williams-Thomas is a former police detective and a multi-award-winning investigative reporter. He is well known for working on investigations, including the "Yorkshire Ripper" Peter Sutcliffe. Williams-Thomas speaks with Insider about special investigative techniques and common issues in the process.