A death by natural causes, as recorded by coroners and on death certificates and associated documents, is one that is primarily attributed to an illness or an internal malfunction of the body not directly influenced by external forces. For example, a person dying from complications from influenza (an infection) or a heart attack (an internal body malfunction) would be listed as having died of natural causes. Old age is not a scientifically recognized cause of death; there is always a more direct cause although it may be unknown in certain cases and could be one of a number of aging-associated diseases. In contrast, death caused by active intervention is called unnatural death. The "unnatural" causes are usually given as accident (implying no unreasonable voluntary risk), misadventure (accident following a willful and dangerous risk), suicide, or homicide. In some settings, other categories may be added. For example, a prison may track the deaths of inmates caused by acute intoxication separately. Additionally, a cause of death may be recorded as "undetermined".