The author's research on police-citizen encounters that resulted in a citizen's death found that excited delirium was often a primary factor. This refers to a state of temporary mental confusion and impaired consciousness associated with emotionally charged, bizarre behavior. Excited delirium may occur under the influence of mental illness, drug effects, or a combination of these factors. In the process of being restrained by police officers and being transported to a police station or hospital, sudden respiratory failure may occur, resulting in death. Officers who observe a person behaving in a manner that suggests excited delirium should summon an ambulance to the scene prior to taking any action to restrain the person. The amount of time taken to achieve restraint and maintain it should be limited. Severe restraints should only be used as a last resort, since that tends to increase the subject's physical exertion. Officers should avoid placing subjects in the prone position if possible, since this restricts breathing. Deaths associated with police encounters may also be related to positional asphyxia (inability to breathe due a particular type of physical restraint) and cardiac arrest. Control and restraint techniques should not involve prolonged restriction of the chest and diaphragm. Upon achieving control and restraint, officers should transport the subject in an ambulance directly to a medical facility for diagnosis and treatment.