Studies distinguishing defendants accused of homicides associated with drug or gang activity from other homicides would be helpful in identifying what, if any, clinical factors are related to lethal violence, the targets of such violence, and possible methods of prevention. Clinical factors appear to play a limited role in homicide in general, but their importance in a minority of specific cases has yet to be fully explored in systematic investigations. Clarification of these dynamics would improve our ability to educate courts and juries regarding the potential role of mental illness in homicide.