A CLUSTER ANALYSIS OF MINNESOTA MULTIPHASIC INVENTORY PROFILES OF 40 MEN CONVICTED OF HOMICIDE WAS CONDUCTED. THE 5 PROFILE TYPES WHICH THE ANALYSIS REVEALED APPEARED TO REPRESENT 2 BROAD CATEGORIES OF PERSONALITY TYPES -- OVERCONTROLLED AND UNDERCONTROLLED INDIVIDUALS. THE OVERCONTROLLED INDIVIDUAL TENDS TO EXERT RIGID CONTROLS OVER HIS EMOTIONS SUCH THAT AGGRESSION AND ANGER ARE SELDOM EXPRESSED, EVEN IN MILD FORMS, UNTIL CUMULATIVE INCIDENTS STIMULATE SUFFICIENT HOSTILITY FOR CONTROLS TO BE OVERPOWERED IN A APPARENTLY IRRATIONAL, UNCHARACTERISTIC AND EXTREMELY VIOLENT ACT. UNDERCONTROLLED INDIVIDUALS, ON THE OTHER HAND, HAVE FEW IMPULSE CONTROLS OPERATING ON A REGULAR BASIS, SUCH THAT AGGRESSION IS A REGULAR PATTERN OF RESPONSE TO FRUSTRATION. THESE RESULTS AND CLASSIFICATIONS OF PERSONALITY TYPES ARE REMARKABLY SIMILAR TO THOSE OBTAINED FROM A STUDY OF 'ABNORMAL' MURDERERS HOUSED AT BROADMOOR HOSPITAL, A MENTAL HEALTH INSTITUTION. THE BROADMOOR STUDY, HOWEVER, REVEALED A SIGNIFICANTLY LARGER NUMBER OF OVERCONTROLLED INDIVIDUALS IN THE SAMPLE THAN DID THE PRISON STUDY OF THE SAMPLE CONSIDERED 'NORMAL.' THE QUESTION IS RAISED AS TO WHY A HIGHER PERCENTAGE OF THOSE ADJUDGED MENTALLY ILL ARE OVERCONTROLLED INDIVIDUALS. A NUMBER OF SPECULATIONS ARE OFFERED CONCERNING THE STANDARDS BY WHICH IT IS DETERMINED THAT CERTAIN OFFENDERS ARE MENTALLY ILL AND REQUIRE HOSPITALIZATION, WHILE OTHERS ARE DEEMED NORMAL IMPRISONED. IT IS ALSO INDICATED THAT RESEARCH NEEDS TO BE DONE TO DETERMINE IF THE TWO GENERAL PERSONALITY TYPES FOUND AMONG MURDERERS ARE UNIQUE TO THIS CATEGORY OF OFFENSEL OR ARE EVIDENCED IN THE BROADER CRIMINAL POPULATION AS WELL. DATA FROM THE STUDY, GRAPHS, AND REFERENCES ARE INCLUDED. (RCB)