Research indicates that memory is impaired in the context of violent experiences, and although hypnosis may enhance accurate recall, it may also lead to false memories. Research shows that bystander nonintervention in violent crimes involves three factors: situational characteristics, bystander personality characteristics, and crime features. Spontaneous vigilantism in response to violent crimes is typically engendered by group support and individual anonymity. The police use of deadly force involves split-second decisions. The decision is influenced by an officer's experience, dispatcher information on the crime and the suspect, and the stimuli received at the crime scene. Coping with the consequences of deadly force involves the impact stage, the recoil stage, and the reorganization stage. Both as victims or shooters, police experience perceptual reactions and posttraumatic symptoms in association with shootings. 33 references.