Factors Associated with Violent Crimes Among Offenders with Mental Illness in Forensic Assessments

Abstract

Abstract Although the media often portrays violent criminal offenders as insane, the crime rate of individuals with severe mental illness is not higher than that of the general population. Social isolation in prisons or general psychiatric hospitals is thus a seemingly futile measures in crime prevention. However, few Asian studies have investigated the risk factors associated with violent criminal offenders with mental illness. The study collected 568 offenses from forensic psychiatric assessment reports completed at a psychiatric center from October 2009 to October 2021, excluding sexual offenses. The offenders were classified as violent offenders or nonviolent offenders. The study analyzed the sociodemographic characteristics, clinical characteristics, and forensic information of the offenders, and assessed their associations with violent crimes. Most offenders (n = 568) were male (74.5%), unemployed (91.4%), and single (92.8%). Compared with offenders without schizophrenia spectrum disorders (n = 287), offenders with schizophrenia spectrum disorders (n = 281) did not have significantly more alcohol use disorder (12.5% vs. 21.3%, p = .007), other substance use disorders (19.2% vs. 16.4%, p = .382), or commit more violent crimes (23.5% vs. 13.8%, p = .209). Men (OR: 2.12; 95% CI: 1.35–3.38) and those diagnosed with alcohol use disorder (OR: 1.62; 95% CI: 1.02–2.57) were more likely to commit violent crimes. Offenders with a diagnosis of intellectual disability (OR: 0.37; 95% CI: 0.19–0.73) were less likely to have commit violent crimes. Alcohol use disorder was the only dynamic factor associated with violent criminal offenders with mental illness.