In this study, cases in which it was difficult to discern whether the death was due to suicide or homicide are examined. To determine the cause of death, the author analyzes the serotonin & histamine levels of the victims. The author describes the method used. He explains that the serotonin content of the injured skin must be at least twice as high as that of a control skin sample to indicate whether the injury occurred before of after death. 2 case histories are presented. (VM)