Schizophrenia and homicidal behavior.

It is generally thought that schizophrenia does not predispose subjects to homicidal behavior. However, many previous studies have suffered from notable methodological weaknesses. In particular, obtaining comprehensive study groups of violent offenders has been difficult. Finnish police have been able to solve about 97 percent of homicides during the last few decades. Because most homicide offenders are subjected to intensive forensic psychiatric examination, we were able to obtain data for 93 homicide offenders with schizophrenia among 1,423 arrested during a 12-year period. Calculations of the odds ratios revealed that the risk of committing a homicide was about 10 times greater for schizophrenia patients of both genders than it was for the general population. Schizophrenia without alcoholism increased the odds ratio more than 7 times; schizophrenia with coexisting alcoholism more than 17 times males.