Serious Mental Illness and Sexual Offending in Forensic Psychiatric Patients.

The role of serious mental illness among those who sexually offend is not well understood. We investigated clinical and risk-related areas of difference between male forensic psychiatric patients with (n = 86) and without (n = 245) a sexual offense history, including the age at which indications of mental disorder and criminal offending first emerged, from a registry of Ontario patients adjudicated Not Criminally Responsible on account of Mental Disorder (NCRMD) from 1999-2012. We further explored motivations for offending among a subset of patients deemed NCRMD for a sexual offense specifically (n = 41). While no differences were found in the age onset of illness or offending across those with and without a sexual offending history, the former group was rated as having higher levels of historical/static risk for violence. Forensic patients with a sexual offense history were also more likely to offend against a stranger, and less likely to offend against a family member. Sexual index offenses were psychotically-motivated in the majority of cases, but with a meaningful proportion appearing to reflect criminogenic motivations, especially substance use and paraphilic interests. Results suggest greater similarity than difference among forensic patients with and without a sexual offense history, but also highlight an important divergence from the literature showing that victims of sexual offenses are frequently known to the individual committing them.