The U.S. medicolegal death investigation system is responsible for investigating and providing determinations of cause and manner of death, playing a vital role in the nation's public health and criminal justice systems. Recent, high-profile deaths in custody cases have drawn widespread attention to the determinations of cause and manner of death made by forensic pathologists, medical examiners, and coroners, and questions have been raised about the scientific validity of such determinations.Strengthening the U.S. Medicolegal Death Investigation System: Lessons from Deaths in Custody evaluates the handling of deaths in police custody by the medicolegal death investigation system and recommends actions to strengthen the nation's medicolegal death investigation system.