Capgras delusion is scientifically important but most commonly reported as single case studies. Studies analysing large clinical records databases focus on common disorders but none have investigated rare syndromes.

Identify cases of Capgras delusion and associated psychopathology, demographics, cognitive function and neuropathology in light of existing models.

Combined computational data extraction and qualitative classification using 250 000 case records from South London and Maudsley Clinical Record Interactive Search (CRIS) database.

We identified 84 individuals and extracted diagnosis-matched comparison groups. Capgras was not ‘monothematic’ in the majority of cases. Most cases involved misidentified family members or close partners but others were misidentified in 25% of cases, contrary to dual-route face recognition models. Neuroimaging provided no evidence for predominantly right hemisphere damage. Individuals were ethnically diverse with a range of psychosis spectrum diagnoses.

Capgras is more diverse than current models assume. Identification of rare syndromes complements existing ‘big data’ approaches in psychiatry.