Abstract: Objective To explore the criminological characteristics and appraisal traits of capacity for responsibility in murder by patients with mental retardation and schizophrenics. Methods 20 cases who were appraised as mental retardation and 58 ones as schizophrenics were retrospectively compared. Results They were similar in gender, age, occupation, casualty and criminal plan , but different in criminal motives, criminal targets, action after crimes, repeated crimes. Conclusion The irritability mental retardation patients and schizophrenics with delusion of persecution or jealousy would be warded strictly. The criminological characteristics is helpful to assess the capacity for responsibility as well as differential diagnose mental retardation and schizophrenics.

Key words: mental retardation, schizophrenia, forensic psychiatry, capacity for responsibility