Geberth (1996) defines a serial murder as "two or more separate murders where an individual, acting alone or with another, commits multiple homicides over a period of time, with breaks between each murder event." The female serial killer typically remains undetected for a significantly longer period of time than the average male serial killer.
Female predators pose a significant challenge to law enforcement personnel, as they are incredibly complex individuals, murdering for specific reasons. Their crimes involve careful, precise and methodical planning. Profiling the typical female serial killer is a complex task. Although incidents are far less frequent that those of male killers, there were almost 100 recorded female serial killers from 1900, with over half of these crimes committed in the United States.
It is generally agreed that most serial killings are premeditated, with the killers preying upon strangers. Motivations are often wide-ranging and anything but simple. It appears that there is a cultural disposition to dismiss genuine criminal potential within a woman and the crimes of male killers are more widely reported. Therefore, they are often able to go on killing over a long period of time, a median of eight years, which is double that of a male serial killer.
Research suggests a number of distinct categories of female serial killer's motives and methods, which are diverse and subtle. The Black Widow systematically murders multiple spouses, partners and family members. The Angel of Death typically murders those who are in her care or rely on a form of medical attention. The Sexual Predator is motivated by acts of a sexual nature. Motives of revenge and jealousy feature in female murders. The Profit/Crime category encompass murders involved in the course of criminal activities.
The female may work in conjunction with at least one other person, usually a male, which would categorize the woman as a Team Killer. They may fall under the Question of Sanity category, where the murders are apparently random and judged legally insane. If not judged legally insane or a definite motive is not established, they are categorized as ‘unexplained.'
The history of murder is replete with dozens of female serial killers, who were far more lethal and successful in their determination to kill than their male counterparts. Examples of female serial killers include Aileen Wuornos, a Florida prostitute who admitted to killing six of her clients between 1989 and 1990. Wuornos spent more than a decade on death row before being executed in 2002. Her life was made into the film Monster, in which Charlize Theron played the starring role.
Another example is Judi Buenoano, who was known as the ‘Black Widow' after she poisoned her husband and drowned her paralyzed teenage son. Buenoano, who also tried to kill her boyfriend, died in the electric chair in Florida in 1998. In 1978, Velma Barfield, a grandmother from North Carolina, was found guilty of the first-degree murder of her fiancé after poisoning him with arsenic, plus three further murders, which included the calculated killing of her own mother. She later said on the killing of her fiancé: "I didn't mean to kill him. I only meant to make him sick." Barfield was executed in 1984.
Every type of person can be a killer, no matter what their background, race or gender. This phenomenon challenges almost every notion as to why human beings destroy one another, from greed and lust to envy and anger. According to The Sourcebook of Criminal Justice, the United States had more than 20,000 murders in 1997, a figure which is constantly rising. It also has the highest recorded numbers of killers globally.
Female serial killers are rarely involved in sexual homicides, the overwhelming motivation for most male killers, unless they are a part of team. The solo female serial killer is typically very careful in planning and carrying out her crimes, often successful at avoiding apprehension a long period of time, if ever. Female crimes also tend to exhibit a different victim typology. The choice of victim usually does not involve reasons due to gender but female killers may exhibit a preference for children, the elderly, a lover or spouse. It is also rare for a female serial killer to attack an adult stranger.