Autistic adults who have a history of committing crimes present a major problem for providers of services in terms of legal disposal options and possible interventions, and greater understanding of this group and their associated needs is required. For this reason, we aimed to investigate the face validity of a proposed sub-typology of autistic adults detained in secure psychiatric hospitals in the United Kingdom. Initially, a focus group was completed with psychiatrists, clinical psychologists, healthcare workers, family members and autistic adults who had been detained in hospital, leading to revisions of the sub-typology. Following this, a consensus rating exercise of 10 clinical vignettes based on this sub-typology with three rounds was completed with 15 psychiatrists and clinical psychologists; revisions to the vignettes to improve clarity were made following each round. The findings indicated that these subtypes possess face validity and raters were able to classify all 10 clinical case vignettes into the sub-typology, and percentage of agreement ranged from 96% to 100% for overall subtype classification. This study suggests that the further validity of the sub-typology should be investigated within a larger study, as these subtypes have the potential to directly inform the hospital care pathway such that length of stay can be minimised.