Rates of mental disorder in people convicted of homicide: national clinical survey

Background. Previous studies of people convicted of homicide have used different definitions of mental disorder. Aims. To estimate the rate of mental disorder in people convicted of homicide; to examine the relationship between definitions, verdict and outcome in court. Method. A national clinical survey of people convicted of homicide (n=1594) in England and Wales (1996–1999). Rates of mental disorder were estimated based on: lifetime diagnosis, mental illness at the time of the offence, contact with psychiatric services, diminished responsibility verdict and hospital disposal. Results. Of the 1594,545 (34%) had a mental disorder: most had not attended psychiatric services; 85 (5%) had schizophrenia (lifetime); 164 (10%) had symptoms of mental illness at the time of the offence; 149 (9%) received a diminished responsibility verdict and 111 (7%) a hospital disposal – both were associated with severe mental illness and symptoms of psychosis. Conclusions. The findings suggest an association between schizophrenia and conviction for homicide. Most perpetrators with a history of mental disorder were not acutely ill or under mental healthcare at the time of the offence. Some perpetrators receive prison sentences despite having severe mental illness.