Motives, Offending Behavior, and Gender Differences in Murder Perpetrators With or Without Psychosis.

Little is known whether differences exist in motivation and reactive/instrumental offense behaviors between murder offenders with and without psychotic disorder. To contribute to better prevention strategies, the aim of this study was to investigate offense characteristics in murder offenders with a psychotic, nonpsychotic or no psychiatric diagnosis, and whether these factors differ according to sex. This data study examined the population of murder offenders between 1997 and 2005 (N = 435) in Victoria, Australia. Apparent motive for murder was allocated to one of six classifications. Assignations of reactive versus instrumental offense categories, co-offending, victim-offender relationship were determined by review of case material. Mental health service usage and prevalence of mental illnesses were identified through data with the statewide register of contacts with the public mental health system. Of the 435 offenders, 43 (9.9%) had been diagnosed with a psychotic illness. Gender differences between a...