Foreword | Homicide is a multifaceted crime, and policies oriented to prevention must be built on solid data and a clear understanding of the various characteristics of homicide and situations in which it might occur. This paper focuses on one such situation: homicide incidents that occur in the course of other crime (for example, during a robbery or a sexual assault).
Of the 4,108 homicide incidents that occurred in Australia between 1989 and 2002, 542 (13 per cent) occurred in the course of another crime. These incidents differ significantly from "non-crime" homicide incidents.
Over the 13-year period, there has been less than one such homicide per week, yet the random and criminogenic nature of these homicides requires the preventive focus to be on violent crime and weapon use.
Homicides caused in the course of another crime are solved in 78 per cent of cases, whereas other homicides are solved in 89 per cent of cases. Most homicides that occur in the course of another crime occur during a robbery (about three-fifths). Whereas two-thirds of homicide victims are men, three-quarters of robbery-homicide victims are men. Whereas one-quarter of homicide victims are aged 45 or older, one-half of victims killed in a robbery are over the age of 45.
The data presented in this analysis have been compiled to further our understanding of the complexity of homicide and to assist police in their work.
Homicide is arguably the most serious offence that can be committed against a person. However, on some occasions, the act of homicide is a "side effect" or unplanned consequence of another criminal act (Maxfield 1989). Such homicides usually involve what Polk (1994) refers to as "double victims"; that is, the victim in the initial crime of robbery or sexual assault becomes the victim in the homicide as well.
Homicides that occur during the course of other crime are commonly classified as "instrumental homicides" because the death of the victim is subsidiary to the primary goal - acquisition of money, property or control (Miethe & Drass 1999). Interviews conducted with convicted robbers indicate that a majority were motivated by instrumental reasons such as getting money or merchandise, or for purchasing drugs (Feeney 1986; Gabor et al. 1987). Most robbers' and sex offenders' initial aim is therefore not to kill their victims, but rather to steal or commit sexual assault. Murder becomes incidental in the sense that it accidentally occurs through the use of excess force - an "eggshell" situation where the victim is susceptible to injury or where the victim resists, resulting in the offender over-reacting.
Based on offence report information collected as part of the National Homicide Monitoring Program (NHMP), an average of 13 per cent of homicide incidents occurring in Australia each year take place during the commission of another crime (42 out of an average of 316 incidents per year). This compares to 17 per cent in the United States in 2001 (Federal Bureau of Investigation 2002), 12 per cent in England and Wales in 2000-01 (Home Office 2002), and 23 per cent in Canada in 20011 (Dauvergne 2002).
Despite yearly fluctuations, the number of homicides occurring during the course of other crime in Australia has remained relatively stable between 1 July 1989 and 30 June 2002 (Figure 1). Over half of the homicides that occurred during the course of another crime, referred to hereafter as "crime homicides" occurred during the course of a robbery (56 per cent). A further 23 per cent of crime homicides occurred during the course of a sexual assault. Eight per cent occurred during a break and enter, and less than five per cent of crime homicides took place following a kidnapping/abduction.
Source: Australian Institute of Criminology, National Homicide Monitoring Program (NHMP) 1989-2002 [computer file]
These figures may under-represent the true incidence of crime homicides in Australia. This is particularly the case for sexual homicide. Burgess and colleagues (1986, p. 252) ascribe the following reasons to this under-reporting of sexual homicide:
- the victim is officially reported as a homicide statistic and not as a rape victim;
- the underlying sexual dynamics in a seemingly "ordinary" murder may not be apparent until the investigation has been completed; and
- conventional evidence of a crime's sexual nature may be absent.
While the trend of crime homicides in Australia is stable, little is actually understood about the nature of crime homicides and how they differ from other homicides.
In recent years there has been a dramatic increase in the rate of robbery in Australia2 (Mouzos & Carcach 2001). In contrast, the rate of robbery-homicide has remained relatively stable over the same period (see Mouzos 2000, p. 74), suggesting that the robbery-homicide trend does not follow the robbery trend in Australia. While there appear to be differences in the incidence rates of the two types of crime, few studies in Australia or elsewhere have examined the proposition that robbery-homicide is a by-product of robbery, and that the only difference between the two is that robbery-homicide results in the death of the victim whereas robbery does not.
One of the few studies that has addressed this question found that robbery-homicides are more similar to other robberies than to other homicides, offering support to the contention that robbery-murder is an intrinsic by-product of robbery rather than a different offence altogether (Cook 1987). This dearth of research leaves many questions unanswered. For example, are the offences of robbery and robbery-homicide essentially similar behaviours that differ principally in outcome rather than in process? Is the typical robbery-homicide most appropriately considered a fatal robbery, or are lethal robberies quantitatively different from non-lethal robberies?
The aims of the present research are thus twofold:
- to undertake a comparative analysis of the circumstances and characteristics of crime homicides and other homicides in Australia; and
- to determine whether robbery homicide is a by-product of robbery, or whether there is some quantitative difference in the two types of crime.
The comparative analysis proceeded in two parts. Part I compared the characteristics of crime homicides and other homicides in Australia using NHMP data. Part II compared the characteristics of robbery and robbery-homicide in Australia based on the limited variables that were available. This analysis was extended to include comparisons of the gender and age of offenders of armed robbery and armed robbery-homicide.
Robbery is defined as:
the unlawful taking of property, with intent to permanently deprive the owner of the property, from the immediate possession of a person, or an organisation, or control, custody or care of a person accompanied by the use, and/or threatened use of immediate force or violence. (ABS 2002, p. 36)
Where a weapon is used in the commission of the offence, robbery is classified as armed; otherwise it is classified as unarmed (ABS 2002, p. 37). The use of personal force (such as hands and/or feet) is considered to be unarmed robbery.
There were three main data sources used for the comparative analyses. These were:
- National Homicide Monitoring Program (NHMP)
- The NHMP was established in 1990, and annually collects information on 77 variables for all homicides coming to the attention of police services throughout Australia. Data are available between 1 July 1989 and 30 June 2002.
- National Armed Robbery Monitoring Program (NARMP)
- Additional offender data on armed robbery were used from data collected as part of the NARMP. This data source has been derived from police records, but is limited to the offence of armed robbery (see Mouzos & Carcach 2001). Data are available between 1996 and 1999.
- Australian Bureau of Statistics (ABS), Recorded Crime Australia
- The ABS collects limited statistics on robbery. The variables include robbery by type of location, gender of victims, age group of victims, type of weapon used, and clearance status. These data were available in aggregate format only, and collection periods also varied for each variable (see notes on Table 2).
(a) Data available from 1995-2001
(b) Data available from 1996-2001
(c) Data available from 1993-2001
(d) Data available from 1997-2001
(e) Excludes homicides committed with physical force (hands and/or feet)
Sources: Robbery - Australian Institute of Criminology, adapted from Australian Bureau of Statistics, Recorded Crime Australia (several years);
Armed robbery - Australian Institute of Criminology, National Armed Robbery Monitoring Program 1996-1999 [computer file];
Homicide - Australian Institute of Criminology, National Homicide Monitoring Program 1989-2001 [computer file]
It is important to note that there were a number of limitations associated with the availability and breadth of data on robbery and armed robbery. Official statistics only collect a standard set of (limited) variables, and the collection of these variables differs on a year-to-year basis. For example, data relating to the gender of victims of robbery and armed robbery were only available from 1995 onwards, and data on age of victims were available from 1996 onwards (see notes at the bottom of Table 2). Given these limitations, the type of analysis was restricted to descriptive statistics, and the chi square test of association was only conducted for the crime and other homicide comparisons.
Part I findings : comparison between crime homicides and other homicides
The comparative analysis of crime homicides and other homicides in Australia reveals a number of noteworthy differences. Compared to other homicides, Table 1 indicates that crime homicides were significantly more likely to:
- occur in a location other than a residential premise (such as a street/open area or recreational venue);
- be unsolved at the time of data collection;
- when offender data were available, involve a victim who was older than the offender (the mean age of crime homicide victims was 41 years and offenders was 29 years, compared to a mean age of 36 years for victims and 34 years for offenders of other homicides);
- involve a male offender;
- involve a victim and offender who were non-Indigenous;
- involve either an unemployed victim, an unemployed offender or both unemployed;
- result from an unknown motive or, where it was known, the motive was related to drugs and/or money or sexual gratification;
- involve a weapon other than a knife or other sharp instrument (firearm, assaultive force, blunt instrument);
- involve a victim and offender who had not been drinking prior to the incident; and
- involve a victim and offender who were not known to each other.
(a) Where an offender had been identified.
Chi-square test of significance: ***p<0.001>**p<0.01>*p<0.05>
Source: Australian Institute of Criminology, National Homicide Monitoring Program (NHMP) 1989-2002 [computer file].
There were no signficant differences found between crime homicides and other homicides in terms of the gender of the victims (males were more likely than females to be victimised in both cases) and the marital status of the victim and offender (both victim and offender were most likely to have been married at some time for both crime types). In sum, these findings suggest that there are certain incident, victim and offender characteristics that are more common to crime homicides than other homicides. The implication of these findings in terms of prevention is discussed further below.
Part II findings : robbery and robbery-homicide in australia
The contrast between robbery and robbery-homicide in Australia is striking (Table 2). Robberies were more likely to be committed in a community setting (52 per cent) or retail setting (30 per cent), whereas robbery-homicides were more likely to be committed in a residential location (55 per cent).
Of those robbery-homicides committed in a residential location, the motive (where it was known) was usually related to getting money (61 per cent) or drugs (16 per cent) and committed by either strangers (54 per cent) or friends/acquaintances (32 per cent). This suggests that there are possibly two types of robbery-homicide occurring in residential premises:
- those that are stranger invasion-type offences where the homicide is an unintentional side effect of the housebreaking; and
- robbery-homicides where the victims and offenders are known to each other and the homicide results from a possible "drug rip-off" or some other confrontation in relation to money.
Table 2 indicates that a disproportionate number of robbery-homicide victims (when compared to robbery victims) were aged 45 years or older (48 per cent versus 21 per cent) and were male (74 per cent versus 65 per cent). Cook (1987) noted similar differences in his analysis of robbery-murder and robbery in the United States. He found that robbery-murder victims were considerably older than either robbery victims or non-felony homicide victims, and that the percentage of robbery-murder victims who were male was higher than the corresponding percentages of either robbery victims or non-felony homicide victims.
The current study reveals a number of other important differences between the two types of crime. The majority of robberies in Australia were unarmed (59 per cent), while only a quarter of robbery-homicides were committed by an unarmed offender. Firearms were used in a higher proportion of robbery-homicides (23 per cent) than in robberies (9 per cent). The comparative analysis also revealed differences in clearance rates for robbery and robbery-homicide in Australia, with robberies having a lower clearance rate (20 per cent) than robbery-homicides (76 per cent).
The present research replicates the results of Zimring and Zuehl (1986) who examined victim injury and death in urban robbery in Chicago, and found that a higher proportion of robbery-homicides (compared to robberies) occurred in a residential location, involved the use of a firearm, and were solved.
Following the examination of robbery and robbery-homicide in Australia, the additional offender variables derived from the NARMP, such as gender and age, were used to compare armed robbery and armed robbery-homicide. The results indicate that, again, males dominate both non-lethal and lethal armed robbery offences (Table 2). There were, however, differences based on the age of the offenders. While most offenders of armed robbery - lethal and non-lethal - were aged between 15 and 34 years, the highest proportion of armed robbery offenders (non-lethal) were aged between 15 and 19 years (34 per cent). However, the highest proportion of armed robbery-homicide offenders were aged 25 to 34 years (28 per cent), suggesting that offenders of armed robberies that result in the death of a victim tended to be older than those offenders in cases where the victim was not killed.
The findings from the comparative analyses suggest that:
- crime homicides are different from other homicides; and
- robbery and robbery-homicide are different and while they can be seen as "endpoints in a continuum representing severity of injury" (Felson & Messner 1996, p. 536), other factors were found to differentiate between them.
There are a number of competing factors that could account for the differences observed between robbery-homicide and robbery. The fact that robbery-homicides were more likely to involve victims aged 45 years or older (of which 44 per cent were aged 65 years or older), is in line with research on the victimisation of older persons that suggests older people may be targeted because they are perceived to offer little resistance to offenders. Due to their increased vulnerability as a function of age - declining physical strength and agility, prospects for post-injury recovery and chances of survival after an attack - older persons may be viewed as "soft targets" or "easy marks". As a result, older persons would be far more likely to be fatally wounded when robbed (Fox & Levin 1991; Maxfield 1989).
While firearms were one of the least commonly used weapons in both robbery and robbery-homicide, the higher use of firearms in robbery-homicide may increase the risk of lethal injury. Zimring (1991) refers to this as the "instrumentality effect". According to this explanation, the likelihood of serious injury or death increases with the lethality of the weapon. Hence, when weapons such as firearms are used, there is a greater likelihood that the victim will be killed than when other weapons or physical force are used (see also Allen 1986; Cook 1980, 1985, 1987, 1990; Felson & Messner 1996; Skogan 1978). This would explain why the greater use of firearms in a robbery-homicide contributes to a higher proportion of deaths than in a robbery.
Differences in clearance status could also be explained in terms of the priority of the police investigation and the seriousness of the offence. The investigation of a robbery-homicide by police will be accorded much higher priority than the investigation of a robbery, mainly because of the nature and seriousness of the homicide component. In terms of severity of response, the criminal justice system may also respond to the robbery-homicide on the same level as other homicides (being the most serious offence), and non-fatal robberies on a less serious level.
Another factor that cannot be discounted is that the death of the victim during a robbery or some other crime may result from differential motivational patterns of the offender. Cook (1987) views the death in these cases as a by-product of the robbery. Some robbery-homicides may be "accidents" that occur because the victim offers resistance to the offender and the offender impulsively reacts with deadly force. Other robbery-homicides result from the offenders' deliberate plan to rob and kill the victim (involving the acquisition of an appropriate weapon). For some robbery-homicides the robbery may be incidental to the homicide, occurring after the victim is killed. The offenders' motivation is paramount to understanding and responding to this type of violence.
It is important to highlight and alleviate public concern about the level of risk of robbery-homicide. The overall risk of death due to robbery in Australia is low. In 2001, the risk of death was calculated at 0.98 per 1,000 robberies (see Maltz 1976 for a discussion of the statistical formula employed). In other words, for every 1,000 robberies there will be about one death. The risk is even lower for sexual homicide.
While the risk of robbery-homicide is low, the findings in the present study suggest a number of avenues for policy formulation and crime prevention. From a crime deterrence perspective, the threat of legal sanction has been proposed as an effective response to instrumental crimes. Recently, the judicial system has also imposed higher penalties for armed robberies committed with certain weapons. For example, the Court of Criminal Appeal in Western Australia recognised that:
use of...a syringe in the course of an armed robbery should, normally attract a sentence of at least one year's imprisonment above that which would otherwise have been imposed for the robbery in question. (Miles v The Queen  17 WAR 578 at 523-524 per White J)3
Measures aimed at improving a person's life skills (such as job training, family counselling and educational enhancement) have been advocated as preventative actions to abate the conditions that motivate instrumental crimes. Prevention also needs to focus on the underlying factors that motivate the offender to commit the crime. The factors that motivate a robbery offender (to acquire money and/or to purchase drugs) will differ from those that motivate a sexual offender (such as power, control or degradation).
To summarise, this research has found that homicides occurring in furtherance of other criminal activity are quantitatively different from non-crime homicides. In addition, the results suggest that robbery-homicides are different from robberies that do not result in the death of the victim. A number of factors associated with the vulnerability of the victims targeted, weapon instrumentality and the priority of the investigative process and seriousness of the offence may account for these differences. These findings further confirm the notion that there is not one type of homicide in Australia, and that the prevention of homicide must therefore be multifaceted and far-reaching.
As promising as these findings may seem, further research in this area is still necessary, especially multivariate analyses examining the factors that increase the probability that a robbery will result in death. Such analysis should include additional variables, such as the involvement of alcohol and/or illicit drugs, and the employment status of both victims and offenders. This could also be extended to include an analysis comparing robbery, robbery with injury, robbery with serious injury and robbery-homicide to further explore the proposition that robbery-homicide is a by-product of robbery. Qualitative analysis of known cases of robbery-homicide would also assist in gaining a greater understanding of what the "trigger" might be that escalates a robbery to a homicide.
The author gratefully acknowledges the constructive comments provided on an earlier draft by the three anonymous referees.
- Australian Bureau of Statistics (ABS) 2002, Recorded Crime Australia 2001, cat. no. 4510.0, Australian Bureau of Statistics, Canberra.
- Allen, R.B. 1986, "Measuring the severity of physical injury among assault and homicide victims", Journal of Quantitative Criminology, vol. 2, no. 2, pp. 139-56.
- Burgess, A.W., Hartman, C.R., Ressler, R.K., Douglas, J.E. & McCormack, A. 1986, "Sexual homicide: A motivational model", Journal of Interpersonal Violence, vol. 1, no. 3, pp. 251-72.
- Cook, P.J. 1990, "Robbery", in N.A. Weiner, M.A. Zahn & R.J. Sagi (eds), Violence, Causes, Public Policy, Harcourt Brace Jovanovich Publishers, San Diego, pp. 85-97.
- --- 1987, "Robbery violence", The Journal of Criminal Law and Criminology, vol. 78, no. 2, pp. 357-97.
- --- 1985, "Is robbery becoming more violent? An analysis of robbery murder trends since 1968", The Journal of Criminal Law and Criminology, vol. 76, no. 2, pp. 480-9.
- --- 1980, "Reducing injury and death rates in robbery", Policy Analysis, vol. 6, no. 1, pp. 21-45.
- Dauvergne, M. 2002, Homicide in Canada, 2001, Juristat, catalogue no. 85-002-XPE, vol. 22, no. 7, Statistics Canada, Ottawa.
- Federal Bureau of Investigation 2002, Crime in the United States 2001, Uniform Crime Reports, United States Department of Justice, Washington DC.
- Feeney, F. 1986, "Robbers as decision-makers", in D.B. Cornish & R.V. Clarke (eds), The Reasoning Criminal: Rational Choice Perspectives on Offending, Springer-Verlag, New York.
- Felson, R.B. & Messner, S.F. 1996, "To kill or not to kill? Lethal outcomes in injurious attacks", Criminology, vol. 34, no. 4, pp. 519-45.
- Fox, J.A. & Levin, J. 1991, "Homicide against the elderly: A research note", Criminology, vol. 29, no. 2, pp. 317-27.
- Gabor, T., Baril, M., Cusson, M., Elie, D., LeBlanc, M. & Normandeau, A. 1987, Armed Robbery: Cops, Robbers and Victims, Charles C. Thomas, Springfield, Illinois.
- Home Office 2002, Criminal Statistics England and Wales 2000-01, Government Statistical Service, London.
- Maltz, M.D. 1976, "Secondary analysis of the UCR: An index of the risk of death due to robbery", Journal of Criminal Justice, vol. 4, pp. 153-6.
- Maxfield, M. 1989, "Circumstances in supplementary homicide reports: Variety and validity", Criminology, vol. 27, no. 4, pp. 671-95.
- Miethe, T.D. & Drass, K.A. 1999, "Exploring the social context of instrumental and expressive homicides: An application of qualitative comparative analysis", Journal of Quantitative Criminology, vol. 15, no. 1, pp. 1-21.
- Mouzos, J. 2000, Homicidal Encounters: A Study of Homicide in Australia 1989-1999, Research and Public Policy Series, no. 40, Australian Institute of Criminology, Canberra.
- Mouzos, J. & Carcach, C. 2001, Weapon Involvement in Armed Robbery, Research and Public Policy Series, no. 38, Australian Institute of Criminology, Canberra.
- Polk, K. 1994, When Men Kill: Scenarios of Masculine Violence, Cambridge University Press, Cambridge.
- Skogan, W.G. 1978, "Weapon use in robbery", in J.A. Inciardi & A.E. Pottieger (eds), Violent Crime: Historical and Contemporary Issues, Sage Publications, Beverly Hills, California.
- Zimring, F.E. 1991, "Firearms, violence and public policy", Scientific American, pp. 48-54.
- Zimring, F.E. & Zuehl, J. 1986, "Victim injury and death in urban robbery: A Chicago study", Journal of Legal Studies, vol. XV, pp. 1-40.
- 1 Excludes homicides that originated during an assault.
- 2 In 2001, the robbery rate was 137 per 100,000 persons, compared to a rate of 72 in 1993.
- 3 See also Pratt v The Queen  WASCA 110 (5 May 2000) and R v Roy  VSCA 61 (2 May 2001).
About the Author
Jenny Mouzos is a Senior Research Analyst at the Australian Institute of Criminology