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Why Some Women Kill Again and Again.

Female serial killers' motives are different than males.

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Monster movie poster
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Contrary to popular mythology, there are indeed female serial killers, and together, they comprise at least 15% of all serial killers. However, the motivations of female serial killers differ significantly from their male counterparts.

In particular, sex is generally much farther down on the list of motivations for female serial killers. In fact, sexual or sadistic motives are extremely rare among female serial murderers. Psychopathic traits and histories of childhood abuse are often found among the very few female serial killers who have sexual or sadistic motives.

Unlike male serial killers who are frequently driven by sexual lust, female serial murderers tend to take a much more pragmatic approach to their killings (1). Female serial killers are much more likely than males to kill for financial profit, comfort or revenge. Unlike male serial killers who usually target unknown victims, females tend to kill men who are emotionally and physically closest to them, particularly husbands or lovers and they generally kill to improve their lifestyle.

However, victims of female serial killers are not confined to male husbands or lovers. An important psychological study of eighty-six female serial killers in the U.S. found that their victims also included children and the elderly (2).

The news and entertainment media have popularized the female comfort/gain killer in the cultural image of the "Black Widow." The black widow serial killer is a woman who murders three or more husbands or lovers for financial or material gain over the course of her criminal career. The black widow killer was featured in the 1944 classic dark comedy film Arsenic and Old Lace starring Cary Grant. This highly popular film tells the fictional tale of two sisters who murder elderly gentlemen by serving them elderberry wine laced with arsenic.

Although they comprise less than 20% of all serial killers, females are very effective in their work and they typically use quieter and less messy methods to kill than their male counterparts (3). The methods they use for murder are more covert or low-profile such as murder by poisoning which was the preferred choice or modus operandi of female serial killers in the aforementioned research study. Other methods of murder that were also identified in the study include shooting, stabbing, suffocation and drowning (4).

Female comfort/gain killers are frequently involved in theft, fraud or embezzlement prior to becoming serial killers due to their interest in material things (5). Although most female serial killers murder for money or other profit, some do it for the attention and sympathy they receive following the death of someone they cared for. It is not uncommon for female comfort/gain killers to be employed as caretakers in nursing homes for the elderly.

Female serial killers generally operate in a specific place that they know well such as their home or a health care facility where they are employed. They rarely go trolling for victims out in the open as male serial killers often do, but rather find victims in their family or workplace.

A notable exception to the typical characteristics of female serial killers is the notorious highway prostitute Aileen Wuornos (portrayed by Charlize Theron in the 2003 film Monster), who killed outdoors instead of at home, used a gun instead of poison, killed strangers instead of friends or family and killed for personal gratification and vengeance. I believe that Aileen Wuornos rose to infamy because she was atypical of female serial killers. The lack of public awareness of female serial killers prior to Aileen Wuornos was due to the virtual absence of female serial killers in the news and entertainment media.

Until Wuornos, the mass media almost always depicted a serial perpetrator as a deranged man due to the erroneous and paternalistic societal notion that women could not commit such crimes. Unlike the obscure and rarely discussed Black Widow killers throughout history, Wuornos became a modern-day celebrity monster and popular culture icon because she defied stereotypes and did not kill demurely as a woman “should.” I present much more about the motivations, fantasies and habits of notorious serial killers, including the “Son of Sam” and “Bind, Torture, Kill” based on my personal correspondence with them, in my book Why We Love Serial Killers: The Curious Appeal of the World’s Most Savage Murderers.

    Dr. Scott Bonn is a criminologist, professor, author and TV analyst. Follow him @DocBonn on Twitter and visit his website


    1. Frei, A., Völlm, B., Graf, M. and Dittmann, V. 2006. “Female serial killing: Review and case report.” Criminal Behaviour and Mental Health, 16 (3), pp. 167-176.
    2. Ibid.
    3. Vronsky, Peter. 2004. Serial Killers: The Method and Madness of Monsters. New York: Berkley Books.
    4. Frei et al.
    5. Vronsky