Aim of the study:
This study aimed to assess the prevalence of homicide in those patients suffered from schizophrenia or bipolar mood disorders and also determine main underlying determinants of this violent behavior in the patients.

Subject or material and methods:
In a retrospective study, the characteristics of 600 consecutive patients hospitalized at Farabi hospital in kermanshah with one of the main diagnosis of schizophrenia or bipolar mood disorders were reviewed. In this regard, diagnosis of schizophrenia (n = 300) and bipolar mood disorders (n = 300) was made by the psychiatric report and based on the DSM-IV criteria. Study information was collected by reviewing hospital recorded files.

Results:
Among schizophrenic patients, 13.3% were committing homicide and homicide offending was prevalent in 20.0% of those with the diagnosis of bipolar mood disorders. In both groups, more than two-third of offending homicide were male and more than half of them were younger than 30 years. In schizophrenics, the main trigger of homicide was delusional beliefs (50.0%) followed by auditory hallucinations (50.0%). Also, in those who suffered bipolar mood disorders, the main triggers of homicide included paranoid delusional beliefs in 73.3%, excitement, irritability and impulsive behavior in 20.0%, and auditory hallucinations in 6.6%.

Discussion:
The observed high prevalence of homicide in these patients highlights the importance of psychopathy assessment among violence-prone individuals with schizophrenia and bipolar mood disorders

Conclusions:
A notable number of our psychological affected patients with schizophrenia or bipolar mood disorders experience homicide that is considerably more prevalent in men, in younger ages, and in those with delusional beliefs