Introduction
Serial murder is a specific type of violence that falls into the crime category of multicide. Multicide distinguishes between the acts of serial murder, mass murder and spree murder. Serial murder is typically defined as a series of three or more separate homicides, with a cooling-off period between each offense, committed at separate locations and involving separate events.
The popular image of serial killers is of evil, disturbed males who roam over wide geographical areas, randomly preying on young women and men. Typically, such definitions are at best oversimplistic, and at worst totally unrealistic. In defining serial murder, discrepancy often occurs as to the number of victims any given offender must kill in order to be termed a serial killer. This important element has been the subject of much debate, and a universally accepted defining number is yet to be found; however, many researchers agree that a serial killer must have a minimum of three to four victims, with the most common number being three victims. Furthermore, many suggest that to include all types of serial killers, the definition must be as broad as possible.
Characteristics of Serial Murderers The ‘typical’ serial killer
From an examination of the research into known serial murderers, it is possible to suggest a number of common characteristics that appear to describe a ‘typical’ serial murderer. Firstly it is well known that the majority of serial murderers are male and that their victims are usually female. Furthermore, serial killing is characteristically perpetrated by white males on white females, with interracial murder being rare. Offenders are typically aged between 25 and 35, which is older than has been found for the more general crime of homicide, and rarely is there a preexisting relationship between an offender and his victims. All serial murderers are motivated to kill and, typically, that motive is intrinsic to each individual murderer; however, it is accepted that sex is often the most likely motive for many serial killers.
African-Americans
While a large number of known serial killers conform to the profile described in Table 1, there is an important group of killers who come from different ethnic groups. In the USA it has been found that 13-16% of serial murderers come from African-American roots. Between 1971 and 1990, there were around 100 cases of serial murder in the USA, 13 of the perpetrators of which were African-Americans. Perhaps the most infamous of such killers is Coral Watts, who has been linked to over 20 sexually sadistic murders between 1974 and 1982 in the states of Michigan and Texas.
Victim choice
It is generally accepted that, in most cases, victims are selected because of their vulnerability; in other words, people who are easier to dominate, such as prostitutes, hitchhikers, the elderly, children and young women. Such people are likely victims not only because of their vulnerability but also because of their accessibility. For example, prostitutes and hitchhikers, by the very nature of their activities, may find themselves willingly getting into the offender’s vehicle, and consequently under his control.
In addition to these victim groups, there are also cases where male offenders murder male victims in homosexually motivated murder (Jeffrey Dahmer, Milwaukee, USA; Dennis Nilson, London, UK). Individuals such as homosexual men, prostitutes and runaway children typically lead high-risk lifestyles and as a result are likely to provide more opportunities for offenders. While this opportunity factor is important in determining who becomes a victim, a potential victim may also have to possess particular physical characteristics before becoming an actual victim. For example, Jeffrey Dahmer cruised downtown Milwaukee exclusively for young, black, homosexual men. In other words, not every vulnerable person who crossed his path became a victim.
Table 1 Common characteristics of serial murderers
| Characteristic | Common characteristic |
| Offender gender | Male |
| Offender age | 25-35 years |
| Offender race | White |
| Victim-offender relationship | Stranger |
| Victim type | Adult, white, females |
| Mobility | Local |
| Motive | Sexual/power/control |
Female killers
Another important group to consider is female serial murderers. While female serial murder is a rarity, there are a number of known murderers, who differ considerably from their male counterparts. Of those which fall into this category, many are ‘quiet’ killers, often working in a caring or nursing environment, such as Beverly Allitt who murdered four children while working as a nurse. She was said to be suffering from Munchausen by proxy syndrome. Others kill as part of a team, usually with a male associate; for example, Myra Hindley and Ian Brady, and Fred and Rose West.
In terms of the differences between male and female killers, female murderers are more likely to use poison to kill their victims. Many, but by no means all, known female serial murderers appear to have been primarily motivated by financial gain. Furthermore, many have been found to have histories of child abuse, extreme poverty and unstable relationships.
Team killers
While serial murderers are typically thought to operate alone, there are a substantial number of cases where murders are committed by two or more individuals together (20-30% of serial murderers are thought to have at least one partner). Some serial killers operate in pairs in order to overpower the victim more easily. Known serial murder teams include Henry Lee Lucus who was helped by his homosexual partner Ottis Toole, and Kenneth Bianchi who killed with Angelo Buono, his cousin. Where the team is made up of a male and a female, the male is often the ‘leader’ and exerts some sort of psychological control over his partner. Together, Douglas Clark and his girlfriend, Carol Bundy, carried out a number of prostitute murders. A commonality often found between such serial murder teams has been their control of their victims through extreme sexual domination.
Prevalence
Serial murder is not a recent phenomenon: cases have been documented as far back as the fifteenth century (Gilles de Rais, who killed several hundred children in France) but there is clear evidence that the phenomenon has increased considerably from 1970 to the present day. It is important to note, however, that this recent increase in serial killer rates is actually a direct reflection of the recent increase in the general homicide rate. Nevertheless, serial murder is on the increase and estimates of the number of serial murderers active in the USA at any one time typically range from 35 to 70. Serial murder is not unique to the USA. Although the incidence of serial murder is far higher in the USA, a similar increase over the last 30 years has been documented in many other countries. In the UK, France and Germany it is estimated that 3-5 serial murderers may be active at any one time, while notable cases have also occurred in Russia, South Africa and Australia.
Explanations for Serial Murder
The cause of serial murder is usually tied to one of three explanations: biological, sociological and psychological; however, it is unlikely that any one theory provides a universal explanation of what causes an individual to become a serial murderer. A complex set of factors and influences mold any one individual into a serial murderer.
Biological explanations
Stereotypically serial murderers are seen as crazed maniacs who are biogenetically predisposed to murder. There is a substantial field of research that addresses biological explanations for murder, ranging from the shape of the head and body to chromosome studies. Trauma, brain damage or genetic traits may cause abnormalities in the brain from birth. Occasionally, there will be serial murderers who, when examined, display abnormalities in their genetic make-up. However, as a rule it is unlikely that biological factors can be given as the sole link between humans and violent behavior. In other words, a blow to the head in childhood or defective genes cannot explain all serial murder.
Psychological explanations
The principal explanation given by psychology and psychiatry for the violent personality is that of the psyhopathic personality. The psychopath can be described as possessing specific behavioral traits, including intelligence, a lack of emotion, insincerity and a lack of remorse, and being without the capacity to love.
Some believe that serial murderers are always psychotic. Certainly some serial sexual murderers, for example Joe Kallinger, have been found to be psychotic. Psychotic individuals experience complete breaks from reality, often seeing visions or hearing voices ordering them to kill.
More recently, disassociative disorder, ranging from daydreaming to complete loss of memory, have been used to explain serial murder. There is also evidence for ‘a divided self’, where part of the personality becomes separate to the offender.
In summary, traditional psychology combines biology with psychotherapy to develop its theories. Typical of such explanations are feelings of sexual and personal inadequacy and repressed rage. The principal flaw in the psychiatric approach is that it neatly places people into categories with vague labels, such as ‘psychopath’. Furthermore, the labels themselves are subject to a great deal of disagreement between psychologists and psychiatrists, and there is no explanation of why sexual and serial murder rates vary from one culture to another.
Sociological explanations
More recently, cultural theories of serial murder have evolved, viewing serial murder as a product of learned behavior and cultural violence. In social structure theory, it is proposed that particular groups of people are more prone to criminality because of their social status. For example, poor people are assumed to be more criminal because poverty prevents their attempts to climb the social ladder. As an explanation, social structure theory is unhelpful, as not all serial murderers come from poor backgrounds. Individuals from all social groups may become serial murderers.
In contrast, social process theory assumes that criminal behavior is a result of the process of socialization. In other words, violence is a behavior learned through exposure and normalization from a young age; however, not all children who are brought up in a violent household end up as serial murderers.
In essence, the sociological approach sees power -having it or not having it, obtaining and maintaining it – as the key element in the explanation of serial murder.
Categorizing Serial Murderers
Much of the information and research into criminals is based on taxonomies or classification systems. Although serial murder is believed to represent a relatively small proportion of all homicides, a number of attempts have been made to classify this group of offenders. Consequently, various typologies of both serial murderers and their patterns of offences have emerged; unsurprisingly, many of them conflict with one another. Some are descriptions of causation; some are based on motivation; and others on murder actions and victim-offender interaction.
Motivation
In serial murder, an obvious motive is often missing. In one empirical study of 203 serial murderers, sexual motivation was the most common, although only 20% gave it as their sole reason for killing. Many also listed enjoyment as a motive. It is generally accepted that serial murder is often a reflection of the desire for ultimate power and control over other human beings. The sexual element present in so many serial murders is an instrument used by the killer to obtain that power and control. One interesting classification system distinguishes between four types of murderer based on their apparent motivation for killing.
Visionary killers are compelled to kill because they have heard voices telling them to do so. Such killers suffer from a severe break from reality and are considered psychotic. The motive is always intrinsic and unique to the killer’s own personality. The crime scenes are usually chaotic, with a great deal of physical evidence available for investigation.
Mission killers are not psychotic but are driven by a desire to rid the world of a particular group of people whom they see as unworthy of living. From the killing they receive a sense of right because, in their eyes, they have made society a better place. Unlike the visionary killer, the mission killer will plan the murders and will therefore leave little physical evidence at the crime scene.
The hedonistic killer murders for the thrill of it. In this category are both the lust killer and the thrill killer. Both kill for personal and sexual gratification. The difference between them lies in the murder acts they commit. The lust killer kills for sex and the crime will reflect a ritualized sadistic sexual fantasy often involving postmortem acts. The thrill killer also kills for sexual gratification but needs the victims to be alive and aware of the degradation being inflicted upon them.
For the lust killer, the crime scene will show evidence of planning simply because the murder will be a result of fantasy that the killer has played over and over in the mind. There may also be evidence of overkill, torture, strangulation and various postmortem injuries and sexual activity.
For the thrill killer, the crime scene will suggest a high level of planning, as the killer needs to be in a ‘safe’ location to allow the time needed to humiliate and torture the victim. In fact the crime scene may never be known to investigators, as the thrill killer often disposes of the victims’ bodies at a separate location. Unlike the lust and visionary killers, thrill killers will not use overkill. They will be highly controlled individuals and there will be little physical evidence at the scene.
There is a third type of hedonistic serial killer, the comfort killer, who’s motivation is material gain. This killer does not kill for sexual gratification, and as a result this type of murder is carried out quickly with no overkill. The crime scene is very controlled and the killer is careful not to leave any physical or forensic evidence.
The final type of murder in this typology is the power/control killer. These killers murder because of a need for complete domination over other human beings. They gain pleasure not from the sexual acts they perform but from knowing that they can do as they wish with the victim. The crime scene will reflect careful planning and control of the situation. Overkill is unlikely and little physical evidence will remain. As with the thrill killer, the victims’ bodies will typically be found at a location other than the murder scene.
Serial sexual murder
The most stereotypical of all serial murderers are those who are in some way involved sexually with their victims. It is a widely held belief, by clinicians and law enforcement alike, that the majority of serial murders are sexual in nature. Consequently, in addition to more general typologies of serial murder, typologies focusing specifically on sexual murder have also been developed. For some researchers, the sexual nature of the crime is viewed as a subtype of one or more general taxonomies.
In general, there are believed to be two types of sex murderers: the rape, or displaced anger, murderer and the sadistic, or lust, murderer. The rape or displaced anger murderers rarely report any sexual satisfaction from the murder, nor do they perform postmortem sexual acts. In contrast, for the lust killer, sex plays an integral part in the murder, often when the victim is already dead. The killing fulfills a need for sexual satisfaction and the murders are likely to be ritualistic, reflecting the killer’s personal and fatal fantasy.
One of the most widely used typologies of lust murderers is that of the organized/disorganized taxonomy developed by the FBI. The two types are proposed to differ in terms of both crime scene behavior and background/personality traits of the killers. Disorganized lust killers are disorganized in all aspects of life: work, home, clothing and demeanor. They are often loners with feelings of rejection and little success at intimate relationships. In terms of the act of murder, disorganized killers rarely plan attacks and the victim is simply an object for violence. Organized offenders are neat in everything they do and are typically egocentric people who are superficially manipulative and charming. They are less geographically constrained and the crimes are planned and committed with some expertise. Table 2 lists the crime scene behaviors and background characteristics that were found to distinguish between the two types.
Mobility
The geographical mobility of serial killers is an area where there is little consensus of opinion and lack of empirical research. Typically, serial murderers are thought to be highly mobile individuals who hunt for victims over a wide geographical area. A number of typologies divide the spatial behavior of serial murderers into categories according to the distances they travel to offend.
Unfortunately, classifications such as those in Table 3 lack some precision, in that no actual distance ranges are suggested to differentiate between the different groups. However, the typologies do draw attention to the vast variations in the size of area over which serial killers may operate. In terms of linking mobility with crime scene behavior, little research has been carried out. It is suggested, however, that disorganized offenders are unlikely to travel very far from home in order to murder, whereas organized offenders are thought to be more mobile and travel considerable distances to kill.
A number of geographical locations are associated with any one murder in a series (e.g. point of encounter, murder scene, body disposal site) and each and every location used by an offender in the commission of a murder is of psychological and investigative importance. While characteristics of the encounter point will play a role in determining whether the murder can be carried out in situ, it can be argued that the stage in the murder process at which an offender chooses to dispose of a body may imply something about that offender, both in terms of mobility and rationality associated with any particular offence. Some researchers suggest that the number of crime locations there are before disposal of the body may reflect the degree of planning a serial murderer has invested in the crime. In other words, the more planned and organized the offence, the more locations involved.
Table 3 Typologies of serial murderer’s mobility
| Mobility | Description of categories |
| classification | |
| Crossing state boundaries, covering | |
| Travellers | thousands of miles |
| Locals | Remain within their home state |
| Place-specific | Do not leave home to kill |
| Geographically | Live in the same area for some time, kill in |
| stable | the same or nearby area and dispose of |
| bodies in the same or nearby area | |
| Geographically | Travel continuously, probably to confuse |
| transient | the police, and dispose of bodies in far- |
| flung places | |
| Hunter | Where an offender leaves homes with the |
| specific purpose of finding a victim | |
| Poacher | Where an offender specifically searches |
| for a victim from a familiar site other than | |
| home or who commutes into another | |
| area to offend | |
| Troller | Where an offender opportunistically |
| encounters a victim during day-to-day | |
| activities | |
| Trapper | Where an offender creates a situation that |
| allows an encounter with a victim in an | |
| environment over which the offender | |
| has control |
Table 2 Crime scene and background characteristics of organized and disorganized offenders
| Type of serial murderer | Crime scene behavior | Background characterises |
| Organized | Plan | Intelligent |
| Use restraints | Skilled in occupation | |
| Commit sexual acts with live victims | Likely to think and plan out the crime | |
| Show or display control of victim | Likely to be angry and depressed at the time of the murder | |
| Use a vehicle | Likely to have a precipitating stress Likely to have a car in decent condition Likely to follow crime events in the media Likely to change job or leave town | |
| Disorganized | Leave weapon at the scene | Be of low birth order |
| Position dead body | Come from a home with unstable work for the father | |
| Perform sexual acts on dead body | Have been treated with hostility as a child | |
| Keep dead body | Be sexually inhibited and sexually ignorant, and to have sexual | |
| Try to depersonalize the body | aversions | |
| Do not use a vehicle | Have parents with histories of sexual problems Have been frightened and confused at the time of the crime Know who the victim is Live alone Have committed the crime close to home/work |
Investigation
The investigation of serial murder poses a particularly difficult challenge for law enforcement. Serial murderers aggravate the difficulties found in all police investigations in two ways: linking cases and identifying the offender. These problems arise from the fact that these murderers are especially difficult to detect. If they were easier to detect, the offender would not have continued to murder time and time again.
The term ‘linkage blindness’ has been used to describe one of the greatest problems in the investigation of a serial murder. Linkage blindness is the lack of coordination and sharing of investigative information between criminal investigation agencies, which may result in crimes perpetrated by the same individual, but in different states or law enforcement districts, remaining unlinked.
Serial murder is typically also a stranger-to-stranger crime, which makes its investigation all the more difficult. Because of this, forensic investigation and criminal profiling play a vital role in the detection of the offender. There is often a wealth of behavioral information left at a serial murderer’s crime scene; this can be used to draw inferences about the type of individual who may have committed such a crime. Such behavioral analysis, combined with a thorough forensic investigation and a consideration of the locations of the offenses, can aid the investigation of serial murder.
