Background. While men with schizophrenia are at higher risk of displaying homicidal behaviours compared with the general population, very little is known about the circumstances related to the triggering of such violent acts among offenders with schizophrenia. The main goal of the present investigation was to describe the surrounding context, psychotic symptoms, target characteristics and other circumstantial factors associated with homicidal acts committed by men with schizophrenia, with or without an additional antisocial personality disorder (APD).

Method. Comprehensive clinical and research interviews, as well as multiple sources of information including reports from social workers and police officers, criminal records, witness statements and questionnaires completed by friends, acquaintances and family members were used to determine specific characteristics surrounding the homicidal acts.

Results. Overall, a significant majority of homicides were considered as the consequence of psychotic symptoms; they mostly involved someone who knew the offender; and they usually occurred in a private residence. However, the subgroup of offenders with both schizophrenia and APD were less likely to be judged as responding to psychotic symptoms; they assaulted a non-relative more frequently, and they were more likely to have used alcohol and to be involved in an altercation with the victim prior to the incident than offenders without APD.

Conclusion. Even for such extreme acts as homicides, the circumstances affecting the occurrence of violence among offenders with schizophrenia may differ when an additional APD diagnosis is present, which would have important implications for prevention and treatment programmes.