Homicidal behavior appears to be a heterogeneous phenomenon. Although the causative role of mental illness in relation to homicide remains a controversial and debatable issue, recent studies indicate that a significant number of homicidal adults suffer from serious mental illness, more specifically psychosis. Most reports that attempt to correlate the presence of identifiable risk factors and homicide yield inconclusive or unreplicated results. In addition to supporting the need for further research in the area of aggressive behavior and violence, prevention also should involve the use of a multidisciplinary approach in considering the multiple causes and solutions to this problem.