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Homicide and Mental Illness

Crime and Mental Illness Fact Sheet Two

Homicide and Mental Illness

Revised September 2004

Quick Quotes

- The rate of homicides by those with serious mental illness has not changed during the transition from large psychiatric institutions to care in the community

- The proportion of homicides by those with a serious mental illness has dropped over the last 30 years, from 20 percent in 1970 to 6 percent in 2000

- The proportion of homicide by those who are mentally well has increased by 3.5 percent a year over the same period

- Serious mental illness has only a small influence on murder rates

- If someone with experience of mental illness commits a murder, mental illness is not necessarily the reason

- Of the 84 people killed by strangers between 1988 and 2000, only two were killed by someone with a serious mental illness

- Homicides committed by people with a serious mental illness do not necessarily indicate a failure of mental health services. Of those with a serious mental illness who murdered, 28.6 percent had no prior contact with mental health services

- Those with a serious mental illness who murder are likely to be older and more likely to be female than those who murder who are mentally well.

Sensational Media Coverage of Homicides Leads to Discrimination

There are around 100 homicides a year in New Zealand, and half of these are murders. The rate is increasing for the general population, but not for those with mental illness. On the rare occasions when someone with a history of contact with mental health services kills, media coverage is often sensational. The end result is a public climate of fear and antagonism towards those who may use mental health services.

However, mental illness is often wrongly linked with particular murders. Speculation that the crime must have been done by a "nutter' or a "madman' is rife in the aftermath of particularly gruesome crimes. The damage is done.

The judicial process may inadvertently fuel the perception that mental illness is linked with violent crime, since people charged with imprisonable offences are quite often remanded for a mental health assessment. Being remanded in this way does not mean that the crime was committed because of mental illness. Unfortunately, some of those who publicise statistics about crime and mental illness use newspaper reports of psychiatric referrals as evidence: this is not good research practice and it inflates the linkage between mental illness and homicide.

Sensational media reporting about mental illness and violence is felt to be the greatest obstacle to reducing stigma and discrimination.

Background Information

New Zealand research

Research has recently been undertaken about the relationship between mental illness and homicide in New Zealand, called Myth and Reality: the Relationship between Mental Illness and Homicide in New Zealand. It looked at every solved homicide in New Zealand between 1970 and 2000. It is important research and finds that there was a decline in the proportion of homicides committed by people with a serious mental illness in the 30 years since the transition from institutional care to community care.

This New Zealand research is internationally significant as it is only the second study in the world that examines a comprehensive range of data showing time-trends on this issue.

"Services are safer, rates of mentally abnormal homicide unchanged, and the public are at relatively lower risk from those with SMI (serious mental illness) than they were in 1970."

A Simpson, B McKenna, A Moskowitz, J Skipworth, J Barry-Walsh, Myth and Reality: the Relationship between Mental Illness and Homicide in New Zealand, Mental Health Research & Development Strategy, 2003

International Research on Homicide and Mental Illness

A United Kingdom study by Taylor and Gunn (1999) showed that the rate of homicides committed by people with mental illness decreased over the period 1957 to 1995, the same time that the move towards community care occurred. The researchers concluded that:

"there is no evidence that it is anything but stigmatising to claim that [people with mental illness] living in the community is a dangerous experiment that should be reversed" (p. 9).

They also found that alcohol and drug problems and personality disorder were conditions associated with greater risk of violent offending than mental illness, and called for better services in those areas.

Taylor, P.J. and Gunn, J. Homicides by people with mental illness: myth and reality. British Journal of Psychiatry, 1999, 174:9-14.

More recently, a national inquiry in the UK, which examined around 1500 homicides over a three year period, provided the following conclusions:

- Only three people per year in the United Kingdom, on average, were found "unfit to plead' and two per year were "not guilty by reason of insanity'

- Five percent of all perpetrators of homicide in England and Wales had a diagnosis of schizophrenia

- Nine percent of perpetrators in England and Wales had been in contact with mental health services in the year before the offence (although this does not mean that they were mentally ill at the time of the offence or that mental illness caused the homicide)

- Around a third of all perpetrators showed some signs of mental disorder, most commonly alcohol dependence, drug dependence and personality disorder. However, most of this group did not have severe mental illnesses and their rate of symptomatology was not a lot higher than for the general population

- It is a myth that offenders with a mental illness are more likely to kill a stranger than offenders without a mental illness.

Safety First: Five Year Report of the National Confidential Inquiry into Suicide and Homicide by People with Mental Illness: Report 2001. London: Department of Health.

Australia's National Homicide Monitoring programme concluded, from a study of nine years of homicide data, that:

- approximately 4.4% of homicide offenders were recorded as suffering from a mental disorder at the time of the homicide

- the overall prevalence of mental disorder in homicide offenders was significantly less than in the general population

The researchers pointed out that their findings contrast with some international studies (such as Safety First, mentioned above) that found that mental disorder is slightly more common amongst those committing homicide offences.

Jenny Mouzos, "Mental disorder and homicide in Australia." Australian Institute of Criminology. Trends and Issues in Criminal Justice no.133, November 1999.

Paul Mullen, in an Australian review, concluded that:

"¡Kpublic perceptions and media claims notwithstanding there is no evidence that deinstitutionalisation and community care have contributed to higher rates of offending among the mentally ill."

Paul Mullen. (2001). Mental Health and criminal justice: A review of the relationship between mental disorders and offending behaviours and on the management of mentally abnormal offenders in the health and criminal justice services. Melbourne: Criminology Research Council. The report is available online at:

Gun Killings

Our earlier fact sheet, The People Most Likely to Kill with a Gun, presented evidence to show that history of mental illness was low on a list of risk factors. Alcohol use, for example, was four times as likely as mental illness to be a precipitating factor in homicide with a gun.

Most murders in New Zealand are committed by people who are closely related to the victim. Around 90% of gun homicides involve a known victim and more than half of gun killings occur in a family violence situation, usually by a male partner.

"Unfit to Stand Trial' and "Not Guilty by Reason of Insanity'

Statistics are available on these legal dispositions for people who have killed and who are judged to be mentally impaired. They apply to only a small handful out of the New Zealand total of around 100 homicides a year. There may be several others each year who, as a result of the psychiatric report, will become special or committed patients. (see Factsheet 3).

For further information contact:

Mental Health Commission,,, Ph: 04 4748900, Fax: 04 4748901, PO Box 1212479, Thorndon, Wellington

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