BackgroundHomicide rates have fallen markedly in the UK over the past decade. There has been little research on whether homicides by people with mental disorder have contributed to this downward trend. Furthermore, there is limited information on trends in court outcomes for people with mental disorder who commit homicide.AimsTo examine trends in general population homicide and homicide by people with mental disorder, and to explore court outcome.MethodWe conducted a national, consecutive case series of homicide in England and Wales (1997–2015). Data were received from the Home Office Statistics Unit of Home Office Science. Clinical information was obtained from psychiatric reports and mental health services.ResultsThere has been a fall in the homicide rate in England and Wales since 2008. Despite this, the relative contribution of mental disorder as a proportion of all homicide has increased. Our findings also showed the inappropriate management of people with serious mental illness convicted of homicide. Of those who committed homicide and were diagnosed with schizophrenia, a third were imprisoned, and there was a marked fall in hospital order referrals. We found this to be linked to substance misuse comorbidity.ConclusionsThe proportional increase in homicide by people with schizophrenia suggests more complex factors may be driving rates, such as substance misuse. Addressing substance misuse comorbidity and maintaining engagement with services may help prevent patient homicide. Despite their complex needs, people with serious mental illness continue to be imprisoned. Improvements in assessment and the timely transfer of prisoners to health services are required.