Homicide is among the most serious of all crimes. Preventing homicide and other lethal violence remains a key priority for Australian criminal justice and law enforcement agencies. The NHMP and its comprehensive collection of data are Australia’s only national system with the capacity to monitor homicide rates and facilitate detailed analysis of homicide types and trends. This analysis provides an important foundation for the development and implementation of evidence-based policy at both the national and state/territory level.
Definition of homicide
In this report, the term homicide refers to a person killed (unlawfully); a homicide incident is an event in which one or more persons are killed at the same place and time. Homicide is defined by the criminal law of each Australian state and territory. As a result, varying definitions exist between states and territories in terms of its degree, culpability and intent. The definition of homicide in the NHMP reflects the operational definition used by police throughout Australia. As such, the NHMP collects data on the following incidents:
- all cases resulting in a person or persons being charged with murder or manslaughter. This excludes driving-related fatalities, except those that immediately follow a criminal event such as armed robbery or motor vehicle theft;
- all murder–suicides classed as murder by police; and
- all other deaths classed by police as homicides (including infanticides), whether or not an offender has been apprehended.
Excluded from this definition is attempted murder and violent deaths, such as industrial accidents involving criminal negligence (unless a charge of manslaughter is laid). Lawful homicide, including that by police in the course of their duties, is also excluded.
There are two key sources of data for the NHMP:
- offence records derived from each Australian state and territory police service, supplemented where necessary with information provided directly by investigating police officers and/or associated staff; and
- state coronial records such as toxicology and post-mortem reports. As of 1 July 2001, the National Coroners Information System enabled online access to coronial findings including toxicology reports.
Where appropriate, the data are further supplemented by newspaper clippings. Newspaper media nationwide are monitored daily by staff at the Australian Institute of Criminology (AIC).
Compilation of this report begins with obtaining police offence reports forwarded directly to the AIC. The NHMP dataset created from these reports is based on 77 distinct variables and the relevant information pertaining to these variables is extracted for each homicide incident and entered into the NHMP database. The information is divided into four key areas:
- an incident file, which describes the case and its circumstances (eg location, date and time of the incident, status of investigation and whether the incident occurred during the course of another crime);
- a victim file, which contains socio-demographic information relating to the victim(s), details of the cause of death and the type of weapon used to kill the victims, and alcohol and illicit drug use;
- an offender file, which details persons who have been charged and includes data on the socio-demographic characteristics of the offender, their previous criminal history, alcohol/illicit drug use, mental health status and relationship to the victim (at all times, the term offender refers to suspected offenders only, and not to convicted persons, unless otherwise stated); and
- a merged incident, victim and offender file, combining details from all three datasets.
It is important to note that not all information collected by the NHMP is available in police offence reports. In many instances, staff of homicide squads or major crime units track down the missing information through other sources (usually by contacting the investigating officer or accessing other information reports) and then supply it to the NHMP. Without this information, there would be many gaps in our understanding of individual homicides and trends in homicides over time. Ultimately, the collection of annual homicide data in Australia is a team effort and is made possible by the continual support of all state and territory police services.
Finally, a rigorous quality-control process is implemented to maximise the accuracy of the NHMP data. This involves crosschecking information contained in each police offence record from additional data sources. As outlined earlier, these supplementary sources include post-mortem coronial reports, information provided by other agencies in the police services (eg statistical services, homicide squads or major crime units and firearms registries) and press clippings. For any discrepancies that may occur between information provided in the police offence report and one of the additional sources, the police source is queried to verify the circumstances. Depending on the reliability of the additional source and the information in response to the NHMP query, the data relating to the homicide incident in the NHMP may be updated accordingly. A report detailing the NHMP quality-control process, entitled Quality Control in the National Homicide Monitoring Program (Mouzos 2002), provides a comprehensive examination of this process and cites examples of identifying inconsistencies in the various data sources. Finally, all of the rates in the NHMP have been calculated using the latest population data from the Australian Bureau of Statistics.