PurposeIndividuals with intellectual disability (ID), mental health needs and criminal justice system involvement are likely to be admitted to forensic units; however, not all of those individuals are served in that system. It is, therefore, important to understand the profile of those admitted to non‐forensic specialized units for individuals with ID and mental health issues. This paper aims to address this issue.Design/methodology/approachDemographic, clinical and criminal profiles of individuals discharged over nine years from a specialized dual diagnosis program were reviewed to delineate clinical subgroups.FindingsA total of 20 out of 84 total discharges were identified as having past or current criminal justice system involvement. The most common offence was assault and 60 per cent of these individuals had admissions longer than one year. Subgroups by psychiatric diagnosis differed in their age, legal status, offence history, and length of hospital stay, as well as in therapeutic interventions and discharge process.Research limitations/implicationsThe results suggest that inpatients with ID and criminal justice system involvement present with unique treatment, support and risk management needs based on psychiatric diagnosis. The number of individuals in clinical subgroups was low, thus further research is needed to determine if the observed patterns hold true in bigger samples.Originality/valueThe study delineates the complexity and heterogeneity of treatment and supports needs of individuals with intellectual disabilities and offending behaviour.