Not guilty by reason of insanity of murder: Clinical and neuropsychological characteristics

We examined archivally clinical status, neuropsychological functioning, and perpetrator-victim relationships of 28 adult patients who had committed homicide and had been subsequently involuntarily committed to a forensic hospital. We divided patients into two groups: (1) not guilty by reason of insanity (NGRI) acquittees (n = 13) and (2) convicted murderers (n = 15). In comparison with convicted murderers, NGRI acquittees were more likely to be seen as psychotic at the time of the index offense and also were more likely to have killed blood relatives, especially a parent. By contrast, convicted murderers were more likely to have killed a significant other, mainly a spouse or lover. At the time of the index offense, substance abuse was more likely to have occurred in the convicted murderers than in the NGRI acquittees. NGRI acquittees and convicted murderers did not differ on neuropsychological tests, with both groups generally scoring within normal limits on all tests. Taken together, these results suggested that NGRI murderers may be driven by acute psychosis directed toward blood relatives and occurring against a backdrop of relatively preserved neuropsychological functioning.