Abstract: Objective To explore the criminological characteristics of mental retardation (MR) in forensic psychiatry. Methods The record scale of forensic psychiatric assessment designed by ourselves was used to analyse the criminological characteristics of 83 offenders with MR, and to compare the criminological characteristics of mild MR with that of moderate and severe MR. Results The mild MR accounted for 62.7%, moderate and severe MR was 22.9%. The percentage of sex offenders in MR was 37.3%, manslaughter 34.7%, property offences 28.0%, respectively. Additionally, 96.1% cases with MR have definite criminal motives, and the criminal history was established in 34.7% cases. Significant differences of criminal premeditation (χ2=11.9,P=0.001), criminal aim(χ2=7.531, P=0.006), criminal motive(χ2=7.920, P=0.019) and criminal types(χ2=7.855, P=0.02) were found between the mild MR and the moderate, severe MR. Conclusions The criminal offenders were mostly found in mild MR. The sex offenders and manslaughter were in outright majority, and most of them had definite criminal motives. The proportion of offenders in mild MR who had criminal premeditation and criminal aim was higher significantly than which in the moderate, severe MR. The proportion of offenders in moderate, severe MR whose criminal motive was for sex was higher than that in mild MR.

Key words: mental retardation, criminological characteristic, forensic psychiatry