Foreword | Building on earlier research undertaken at the Australian Institute of Criminology (Pinto & Wilson 1990), the current research explores the serial murder phenomenon in Australia using data collected as part of the Institute's National Homicide Monitoring Program (NHMP). Results show that between July 1989 and June 2006, there were 11 groupings of serial murders identified in the NHMP, committed by 13 known serial murder offenders, with a total of 52 known victims. This represents one percent of the total number of homicides in Australia over a 17 year period. The paper reports on the characteristics of offenders and victims, including the offenders' modus operandi. The analysis found that the profile of serial murder in Australia is similar to that found in international research. In at least two of the groups of serial murders the victims had been reported as missing to police. It is important to note that the paper reports on known homicides. The paper suggests that further research on the profile of long term missing persons and serial murder victims should be undertaken as well as exploring offenders who commit multiple murders on separate occasions, to identify what prevented them (apart from law enforcement intervention) from committing additional murders.
Despite public fascination with, and interest in, the serial murder phenomenon, little research on this topic has been undertaken in Australia. High profile cases such as the backpacker murders in New South Wales and Snowtown murders in South Australia serve to heighten the public's awareness, and perhaps overstate the threat, of serial murder in Australia. This contributes to a lack of understanding of serial murder, especially regarding the offender profile and the likelihood of victimisation. Building on earlier research by Pinto and Wilson (1990), this study aims to examine the circumstances and characteristics of serial murders that have occurred in Australia since the inception of the NHMP in July 1989.
Definition of serial murder
There is a lack of consensus among academics and practitioners in the definition of serial murder. Disagreement centres on the number of victims, the presence/absence of a sexual element, and the common characteristics of victims (Egger 1998; 1984; Holmes & DeBurger 1998; Dietz, Hazelwood & Warren 1990; Myers et al. 1993; Cantor et al. 2000; Fox & Levin 2005). In order to include all types of serial killers, a broad definition of serial murder is used in the current research. In accordance with the crime classification manual developed by the FBI, serial murders are those that involve three or more separate events (Douglas et al. 1992), and most importantly, are repetitive sequential homicides of any nature. Frequently, serial murders involve a similarity of subject or purpose (for example, the choice of victims, methods of killings, or the killer's motivation; Aki 2003: 6).
Review of the literature
Characteristics of serial killers
Serial murder has been described as deliberate, premeditated, and sexually predatory in nature, with a lack of interpersonal conflict and provocation (Kraemer, Lord & Heilbrun 2004: 338). The characteristics of serial killers - their behaviour, actions and motivation - are diverse, intricate and include cross-cultural variations (Folino 2000: 740).
When a motive is ascribed to the killing in serial murder it is usually characterised as either sexual or psychological gratification (Egger 1998). Sex is used by the serial killer to achieve power and control over their victim, as opposed to sex being an end in itself (Egger 1998). In a study of 494 known serial killers across the United States, almost two-thirds were motivated by the thrill of power or sexual sadism (Fox & Levin 2005).
International research has found a number of common characteristics among serial killers and their murders:
- serial murder is predominantly committed by white/Caucasian males of moderate to high intelligence (Aki 2003; Kraemer, Lord & Heilbrun 2004; Fox & Levin 2005; Rule 1986 cited in Holmes & DeBurger 1998)
- serial killers are usually aged in their mid-twenties with a mean age of 30, and the typical age range between 25 and 40 years (Aki 2003: 17; Kraemer, Lord & Heilbrun 2004; Godwin 1999)
- serial killings are usually intra-racial (Hazelwood & Douglas 1980; Hickey 2006)
- serial killers are more likely to act alone (Kraemer, Lord & Heilbrun 2004)
- serial killers most commonly use strangulation or beating as a means of killing (Kraemer, Lord & Heilbrun 2004)
- male serial killers are more likely to use strangulation, stabbing, ligature weapons, hands or feet (beating), cause injury to victim's head and genitalia (anus), bind victims and sexually assault victims (Kraemer, Lord & Heilbrun 2004: 336)
- female serial killers are relatively uncommon - an overseas study of 200 serial killers found 12 to 17 percent were women (Hickey & Holmes 1991)
- female serial killers were motivated by a need for financial security, revenge, enjoyment, and sexual stimulation (Hickey & Holmes1991; Riedel 1998)
- female serial killers who act alone are more likely to use poison as a method of killing (Kelleher & Kelleher 1998)
- serial killers usually premeditate their crimes, frequently fantasising and planning with detail, including the specific victim (Ressler, Burgess & Douglas 1988)
- serial killers are likely to use similar event locations (but different physical locations) for their crimes, move the body from one location to another and dispose of the body in remote locations (Kraemer, Lord & Heilbrun 2004).
Studies of the backgrounds of serial killers have found possible links between serial murder and childhood animal cruelty (Wright & Hensley 2003; Jenkins 1988); persistent bedwetting; arson (Douglas & Olshaker 1999); prior sexual offending (Francis & Soothill 2000); and childhood neglect and social and psychological deprivation (Riedel 1998; Wright & Hensley 2003; Power 1996; Jenkins 1988). However, it has been argued there is an 'overemphasis on environmental or biological determinism' as a means of diffusing the responsibility of serial killers for their crimes (Fox & Levin 2005: 113).
Characteristics of victims
While the victims of serial killers are diverse, a serial killer usually selects a 'type of victim' (Ressler, Burgess & Douglas 1988). Victims of serial killers have been noted to share common characteristics such as age, appearance, occupation, hairstyle, lifestyle and race.
Overseas research indicates victims are usually young, vulnerable Caucasian women (Kraemer, Lord & Heilbrun 2004). Serial killers also tend to target other vulnerable victims such as children, the elderly, the homeless, prostitutes or mentally retarded persons (Kraemer, Lord & Heilbrun 2004: 330). Victim selection tends to be based on easiest access for the serial killers (Aki 2003: 20).
Male serial killers generally tend to target prostitutes, women, or young boys or girls as victims, usually strangers. Female serial killers generally target victims whom they know and with whom they have shared some kind of relationship, with more than 70 percent targeting family members or persons who are dependent on them (for example, patients; Fox & Levin 2005). Female serial killers commonly commit filicide or infanticide (Aki 2003), usually natural-appearing deaths (for example, poisoned infants).
It has been suggested that victims are most likely spatially biased toward the serial killer's home centre. Serial killers in general target locations they know best, concentrating on potential victims within their immediate environments and surrounding areas (Brantingham & Brantingham 1981; Godwin & Canter 1997).
Types of serial killers
While forensic techniques and, in recent times, behavioural evidence analysis assist in establishing the differing types of serial killers (see Turvey 2002), there are sociological, psychological, cultural, and biological explanations for the motivations of serial killers (Egger 1998).
A common classification of serial killers is the organised-disorganised typology, where personality characteristics of serial killers are determined from crime scene information (Ressler, Burgess & Douglas 1988). Criminal behaviour is analysed in terms of the level of organisation in the perpetration of the crime, such as planning, isolation of the victim, control of the victim, manner of killing, disposal of the body, post-mortem mutilation, concealment, escape, timing and victim selection (Pakhomou 2004: 228).
One study of serial killers applied another dichotomy for historical depth: habitual-dedicated, where perpetrators were analysed on a scale of their criminal versatility. Serial killers who committed three or fewer types of offences (burglary, robbery, drug offences, sexual offences etc), were considered to be dedicated offenders (in terms of their dedication to specific crimes of murder), while offenders who committed six or more types of offences were characterised as habitual offenders (Pakhomou 2004: 228). The study found that the majority were organised and dedicated. In the disorganised and mixed groups, equal numbers were dedicated and habitual (Pakhomou 2004). Additionally, a 'prototypical serial killer' is not only organised in the criminal activity, but highly specialised in terms of sexual offences as well (Pakhomou 2004:229).
As an extension of the organised-disorganised construct, another common typology categorising four major types of serial killers was developed. It attempts (perhaps too simplistically) to assign an either/or status to serial killers based on a socio-emotional and psychological assessment (Holmes & DeBurger 1998). The classified types are:
- Visionary - driven to kill by voices or visions, either from God and angels or demons and the devil.
- Mission-oriented - concentrates on the actual killing and its outcome. They see it as their duty to eliminate individuals they consider unworthy or undesirable, such as prostitutes, from society.
- Hedonistic - divided into two sub-categories of lust killer and thrill killer. The central focus for the lust killer is sex; before, during or after the killing. For the thrill killer, the act of killing is simply for enjoyment, pleasure or excitement.
- Power/control - motives are the pleasures received from complete control and dominance over the victim. The killer feels important and powerful. Prolonging the act ensures greater gratification (Holmes & DeBurger 1998).
Over the years the original typology developed by Ressler and colleagues (1988) of serial killers has been divided and sub-divided - killers are categorised as organised, disorganised, assertive, reassuring, commuters, marauders, missionaries, hunters - each with their particular features (Warwick 2006: 566).
In sum, previous overseas research (predominantly undertaken in the US) suggests serial killers are mostly white males in their 20s or 30s, of above average intelligence, who usually commit intra-racial murders of strangers (Pakhomou 2004: 219). It also suggests that most serial homicides are sexual in nature (Ressler, Burgess & Douglas 1988). One of the questions in the current research is whether these patterns hold for Australian serial killers.
Purpose of current research
This research examines the characteristics of serial killers, their murders and victims. Specifically, the purposes of the research are to:
- identify the incidence of serial murder in Australia since 1989
- identify the characteristics of serial murder offenders, including their modus operandi, signature and antecedent behaviour
- identify the characteristics of the victims of serial murder to develop a victimology profile
- compare serial murder with homicide in general.
The research used homicide data compiled by the AIC's NHMP as the primary data source. These data were supplemented with information from state and territory law enforcement agencies.
In brief, the NHMP has collected information on all homicides known to police across Australia since 1 July 1989. Information is collected on the circumstances and characteristics of homicide incidents (location, number of offenders, etc), victims and offenders (sociodemographic characteristics, illicit drug/alcohol involvement), and the relationship between the victim and offender. For a review of serial murder in Australia prior to 1989 see Pinto & Wilson (1990) and Kidd (2006).
Between July 1989 and June 2006, 5,743 homicide offenders killed 5,617 victims in a total of 5,226 homicide incidents in Australia. During this period, 11 groupings of serial murders were identified in the NHMP (see Table 1). The total victim count (where known) per serial murder grouping ranged from a minimum of three (as per definition) to a maximum of 12.
|Incident year(s)||Gender of offender||Type||Number and gender of victims||Modus operandi||Motive|
|(a): One 1974 murder has been included in the counts as it occurred as part of a series of murders otherwise occurring in this period|
|Source: AICNHMP 1989-2006 [computer file]|
|1992-99||4 males||Power control orientated||10 males; 2 females||Victims all known by at least one offender; bodies of victims dismembered||Financial gain and dislike towards obese persons, homosexuals and paedophiles|
|1993||Male||Mission oriented||3 females||Waited for the victims on the street; told them he had a 'gun' which was a piece of aluminium piping; victims violently stabbed||Hatred of women|
|1989-92||Male||Power control oriented||1 male; 6 females||Picked up hitchhikers on the road; overpowered them with a firearm; victims received multiple stab wounds||Power and control|
|1998-99||Male||Hedonistic||4 females||Attacked on the street, overpowered and put in the boot of the car, throat slit||Psycho-sexual|
|1998||Male||Mission oriented/ power control||2 males; 1 female||Disabled pensioners strangled to death||Possible financial gain (money for drugs); viewed killing as an achievement|
|1997-2001||Male||Power control oriented||3 females||Blitz, frenzied attack with a knife from behind; multiple stab wounds||Psycho-sexual|
|1989-90||Male||Mission oriented||6 females||Assaulted with claw hammer then strangled with own pantyhose||Hatred of older women, financial gain|
|1974-90||Male||Hedonistic||1 male; 3 females||Strangulation, objects stuffed in mouth||Psycho-sexual|
|1989, 1990, 1992, 1999||Female||Visionary||2 males; 2 females||Suffocation||No apparent motive|
|1996||Male||Hedonistic||3 males||Stabbing, shooting||Gang related|
|1996-97||Unsolved||Not known||3 females||Abducted from the street within close vicinity of each other||Not known|
These serial murders involved 13 known killers (excluding the Claremont killings in WA - while these murders are unsolved, it is suspected that a sole offender was responsible, based on the similar modus operandi in each case). All but one grouping of serial murders were committed by an offender acting alone, and 12 of the 13 identified serial killers were male. Where information was known, the majority of the serial murderers were unemployed when apprehended by police.
The total number of known victims is 52 (including the three Claremont murder victims), with serial murder accounting for less than one percent of all homicides in Australia. It is possible that the victim count may be greater due to as yet unidentified connections between murders.
The majority of serial murder victims in Australia were female (n=33; 63%), which is in contrast to the general pattern of homicide where males outnumber females as victims (see Mouzos & Houliaras 2006). The youngest victim was aged three weeks and the oldest was 92 years. The average age of victims was 31.5 years. In terms of racial appearance of the victims, the majority were Caucasian (where information was known). There was only one Asian serial murderer. The serial murders were predominantly intra-racial.
A number of commonalities were noted among the victims, indicating that serial killers may have specifically targeted them. In accord with the findings of previous international research, vulnerable groups such as the very young, the elderly, and disabled pensioners were targeted, as were persons in easily accessible locations, such as hitchhikers.
In several series of serial killings, the victims were abducted from an outdoor location and either killed at that location or taken elsewhere and killed. Victims who were killed in a residential location usually knew the offender.
In most cases, the victims were killed with a knife, and it was common to find that they had suffered multiple stab wounds. In three series of serial killings involving predominantly elderly victims, the victims were strangled to death with a ligature. In two series of serial killings, the offenders used a firearm or the pretence of firearm to overpower their victims and demand obedience (Table 1).
While overseas research suggests that serial murder is predominantly perpetrated by persons not known to the victims, in the case of serial murder in Australia, 25 victims did not know their attacker (stranger homicides) while 24 victims knew their attacker, either intimately or as an acquaintance.
Much research has found a sexual element to be common in the murders committed by serial killers. Based on the information available in the NHMP case files, there is sufficient evidence to suggest that six out of the 11 series of serial killings involved a sexual element. This could include evidence that the victims were sexually assaulted, or of sexual overtones in the crime scene or torture of the victims. In all but one of these serial killings (one series remains unsolved), the victims and offenders were not known to each other.
Five of the 13 serial killers had a history of prior sexual offending, and one offender was described by the sentencing judge as a 'sexual predator of the worst kind'.
The antecedent behaviour of the serial killers was also examined. Where information was available, a history of engaging in animal cruelty was found in the backgrounds of three of the serial killers. Another three serial killers had experienced childhood sexual abuse, and the only female serial killer's mother was murdered by her father when she was two years old. While not considered antecedent behaviour, two serial killers were heroin users.
Typology of serial murder
Table 1 outlines a typology of serial murder in Australia based on that developed by Holmes and DeBurger (1998). These categories are not necessarily mutually exclusive, especially when a serial killer exhibits characteristics of two or more typologies. This is one of the criticisms of the typology (see Canter & Wentink 2004), and is an indicator of the inherent weakness in trying to group complex human behaviour into specific categories which tend to overlap.
An attempt to group the 11 Australian serial murders suggests they are distributed equally across the categories of power/control, mission and hedonistic with three series falling in each of these categories (see Table 1). The one series involving the female offender was allocated to the visionary category.
A degree of overlap was found between the typologies. For example, the first series of serial murders could be described as both power/control oriented as well as mission oriented, as the offenders saw it as their duty to eliminate homosexuals and paedophiles from society (Table 1). Two of the serial killers who committed mission oriented serial killings had a hatred for women. When one of the serial killers was questioned by police as to why he killed the women, his response was 'I just hate 'em'. Another serial killer's response in relation to his motive was 'To me, I think of it as an achievement, because I have achieved absolutely nothing in my lifetime... to murder and to get away with it was an achievement... at the point of killing... I didn't care'.
Comparison with homicide in general
Results of a comparison of serial murder with homicide in general indicate that serial murder is quite different. A typical homicide in Australia involves a male aged in his 30s killing a male friend or acquaintance with a knife in a residential location. The murder is usually the result of an argument (Mouzos & Houliaras 2006). In contrast, the current study indicates that serial murder most commonly involves vulnerable victims, usually multiple adult females killed by a single male offender in a non-residential location with a knife or ligature strangulation. A sexual element is not uncommon in these killings, and the offender is not intimately known to the victims. This profile of serial murder in Australia is similar to the profile depicted by international research.
Implication of the findings
Research into under-studied areas serves to highlight gaps in knowledge and to test assumptions against facts. Over the 17 year period examined in this study, there were a total of 52 known victims of serial killers in Australia, representing less than one percent of the total number of homicide victims. While the risk of becoming the victim of serial murder in Australia is relatively low, it is important to examine ways in which the current knowledge base can be applied to practice, by informing police investigations in other areas, such as missing persons.
The fact that there was an almost equal split between stranger and non-stranger victim-offender relationships is an important finding. In the stranger murders, the majority of victims were female, the crimes involved a sexual element and the victims were abducted from outdoor locations.
In at least two of the series of serial murders examined in this study, the victims had been reported missing to police. A number of persons reported missing each year fit the criteria of being female, young and able to be influenced easily. Drugs and/or alcohol and mental impairment also feature in this group (see James, Anderson & Putt forthcoming). While the exact number of missing persons who exhibit characteristics similar to serial killer victims is unknown, it is worthwhile to compare the characteristics of serial murder victims with those persons reported missing. This may enable the level of risk of missing persons becoming a victim of serial murder to be gauged. Further research is required to examine this, and also to test the possibility of a link between the two, and whether the profile of long-term missing persons compares with the profile of serial murder victims.
Conceptual limitations: definitional blindness
One of the issues highlighted earlier is the definition of serial murder. There are several definitions of serial murder, with variations based on the number of victims. The insistence on a body count of three is problematic, in that it may be seen as more of a counting exercise than an indicator of a serial killer's state of mind or criminal intent. For example, a killer who murders two victims and is apprehended by police prior to committing additional murders, and who exhibits the same or similar characteristics as one who kills five, is also important to our understanding of this phenomenon. The adoption of a number or quota system is counterproductive to understanding and developing appropriate responses to this crime type. The ability of law enforcement agencies and the wider community to understand and manage the risk posed by the serial killer is intrinsically linked to a comprehensive understanding of the dynamics of the individual and the motivating factors.
Given the low incidence of known serial murders in Australia, further research could focus on examining those offenders who commit two rather than three or more homicide incidents in a series. Comparing these murders with the serial murders examined in this study could lead to a more thorough understanding of the offender who commits more than one murder on separate occasions. This includes exploring the most important question as to what, apart from apprehension by a law enforcement agency, prevented them from committing more murders.
The authors gratefully acknowledge Tina Houliaras, a former research assistant at the AIC for her assistance with the review of the literature.
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About the Authors
Dr Jenny Mouzos is a senior research analyst and Manager of the Crime Monitoring Program at the AIC.
David West is the Intelligence Coordinator in charge of the New South Wales Police Homicide Squad Intelligence Unit.