While no criteria can definitely predict an individual's dangerousness, several factors might indicate the need for a preliminary assessment: history of mental illness, present mental illness, relationships with others, perceived grievance that has increased in significance recently, history of attempts to contact a protected person, and current mental and physical capacity to develop a plan and act in a sustained, organized fashion to implement that plan. A more formal evaluation should focus on short-range behavior, with attention to dangerous situations involving a specific subject, a victim, and an act under specific circumstances. Recommendations on interviewing a potentially dangerous person address the setting and the questioning technique, emphasizing that a male-female interview team can obtain maximum cooperation from the subject. Guidelines to the selection and training of interviewing agents consider desirable personality characteristics and methods to teach assessment of mentally ill subjects in hospital, academy, or on-the-job settings. The authors also propose that the Secret Service increase opportunities for agents to consult with mental health professionals, appoint a national mental health and behavioral science advisory group, and develop a standard investigation record and computer capacity for making records accessible to agents. A memorandum on assessing potential female assassins suggests that agents question women suspects about their relationships and use settings that are relatively free from tension and fear. The appendix provides an outline of items that a standardized investigative record on a potential assassin should include.