Mental illness falls into the category of mitigating circumstances in capital offenses. Research conducted by Palmer on the subject of early life experiences and their effect on frustration and aggression indicates that socialization significantly affects aggression. Palmer's research indicates that murderers were not only exposed to severe early frustration but were also undersocialized. He contends that childhood trauma materializes as post-traumatic stress disorder (PTSD). The relationship between early trauma and later frustration has become clearer since the advent of the DSM-III (Diagnostic and Statistical Manual of Mental Disorders, Third Edition). The DSM- III contains diagnostic criteria for PTSD and includes criteria for assessing the link between substance abuse and impulsive behavior. Implications of mitigating circumstances related to mental illness and substance abuse in violent crime are discussed in the context of capital punishment. 17 references