A LITERATURE REVIEW WAS CONDUCTED TO IDENTIFY CLINICAL, DIAGNOSTIC, AND PROGNOSTIC FEATURES OF MURDERERS, AND THESE FEATURES WERE THEN CLUSTERED IN THE THREE STUDY CATEGORIES. CASE HISTORY AND CURRENT BEHAVIOR DATA OF THE 20 CRIMINAL SUBJECTS AND THE 10 CONTROLS (RESIDENTS OF A MENTAL HOSPITAL) WERE ENTERED ON THE STATISTICAL AND EVALUATIVE FORMS PREPARED FOR THE STUDY. RESULTS OF ANALYSIS DO NOT SUPPORT THE PRESENCE OF A WELL-CRYSTALIZED PREDISPOSITION FOR HOMICIDAL BEHAVIOR IN THIS POPULATION, BUT SHOW THAT THE ADOLESCENTS WHO COMMITTED HOMICIDE WERE PSYCHOTIC-REGRESSIVE AND THOSE WHO THREATENED OR ATTEMPTED MURDER WERE ORGANIC-IMPULSIVE. ALTHOUGH THE MAJORITY OF MURDERERS HAD A CHRONIC SCHIZOID ADJUSTMENT AND AN INTENSIVE SYMBIOTIC RELATIONSHIP WITH THEIR MOTHERS, AND EVIDENCED MARKED SEXUAL INHIBITION AND SEXUAL IMMATURITY, AN ASSOCIATION BETWEEN HOMICIDAL TENDENCIES AND THESE FACTORS CANNOT BE INFERRED. ENVIRONMENTAL FACTORS (PARENTAL BRUTALITY, EXPOSURE TO VIOLENCE OR MURDER AMONG FAMILY MEMBERS, INCESTUOUS ASSAULT BY A PARENT, AND AVAILABILITY OF FIREARMS IN THE HOME) APPEAR TO BE MORE DETRIMENTAL TO THE PREHOMICIDAL DISPOSITION OF THE MURDERERS THAN TO THAT OF THE JUVENILES WHO ATTEMPTED OR THREATENED MURDER. TABULAR DATA AND REFERENCES ARE PROVIDED. (DAG)