In essence serial murderers should include any offenders, male or female, who kill over time. Most researchers agree that serial killers have a minimum of 3-4 victims, and the FBI Symposium in 2005 reduced the number to a minimum of 2 victims. Usually there is a pattern in their killing that may be associated with the types of victims selected or the method or motives for the killing. This includes murderers who, on a repeated basis, kill within the confines of their own home, such as a woman who poisons several husbands, children, or elderly people in order to collect insurance. In addition, serial murderers include those men and women who operate within the confines of a city or a state or even travel through several states as they seek out victims. Consequently, some victims have a personal relationship with their killers and others do not, and some victims are killed for pleasure and some merely for gain. Of greatest importance from a research perspective is the linkage of common factors among the victims-for example, as Egger (1985) observed, “victims’ place or status within their immediate surroundings (such as vagrants, prostitutes, migrant workers, homosexuals, missing children, and single and often elderly women)”. Commonality among those murdered may include several factors, any of which can prove heuristic in better understanding victimization.
Much of our information and misinformation about criminal offenders is based on taxonomies, or classification systems. Megargee and Bohn (1979) noted that researchers usually created typologies based on the criminal offense. This invariably became problematic because often the offense comprised one or more subgroups. Researchers then examined repetitive crime patterns, which in turn created new complexities and problems. Megargee and Bohn further noted that, depending on the authority one chooses to read, one will find between two and eleven different types of murderers (pp. 29-32). Although serial murder is believed to represent a relatively small portion of all homicides in the United States, already researchers have begun the difficult task of classifying serial killers. Consequently, various typologies of serial killers and patterns of homicides have emerged. Not surprisingly, some of these typologies and patterns conflict with one another. Some are descriptions of causation, whereas others are diagnostic in nature. In addition, some researchers focus primarily on individual case studies of serial killers, whereas others create group taxonomies that accommodate several kinds of murderers.
Wille (1974) identified ten different types of murderers covering a broad range of bio-socio-psychological categories:
- afflicted with organic brain disorder
- passive aggressive
- juvenile (the child was the killer)
- mentally retarded
- sex killers
Lee (1988) also created a variety of labels to differentiate killers according to motive, including:
- power or domination
- contract killing
Even before American society became aware, in the early 1980s, of serial murder as anything more than an anomaly, researchers had begun to classify multiple killers and assign particular characteristics and labels to them. Guttmacher (1973) described the sadistic serial murderer as one who derives sexual gratification from killing and who often establishes a pattern, such as the manner in which they kill or the types of victims they select, such as prostitutes, children, or the elderly. Motivated by fantasies, the offender appears to derive pleasure from dehumanizing his or her victims. Lunde (1976) recognized and noted distinctions between the mass killer and the serial killer, notably that the mass killer appears to suffer from psychosis and should be considered insane. By contrast he found little evidence of mental illness among serial killers. Danto (1982) noted that most serial murderers may be described as obsessive-compulsive because they normally kill according to a particular style and pattern.
Researchers have been attempting to create profiles of the “typical” serial killer from the rapidly accumulating statistics on offenders and victims in the United States. The most stereotypical of all serial murderers are those who in some way are involved sexually with their victims. It is this type of killer who generates such public interest and alarm. Stories of young women being abducted, raped, tortured, and strangled appear more and more frequently in the newspapers.
-Eric Hickey, Serial Murderers and Their Victims