Early Postmortem Changes

Dying and death are continuous biological processes. In the great majority of cases, individual death is attributed to irreversible cessation of respiratory and circulatory functions. Circulatory and respiratory arrest are followed by early postmortem changes such as postmortem lividity and rigor mortis. However, metabolism of tissues continues for some hours after death. In this supravital period, reactions of tissues on excitation are much like those in life. Supravital reactions as well as the time-dependent criteria of postmortem lividity and rigor mortis are used for estimating the time since death. The early postmortem changes are completely different in nature: Body cooling and postmortem lividity are predominantly physical processes. Rigor mortis and supravital reagibility of skeletal muscle are physicochemical processes. Of importance is further cooling of the body due to convection, conduction, radiation and evaporation. A mathematical expression of rectal cooling after death was published by Marshall and Hoare (1962), who took into account the whole sigmoidal shape of the cooling curve. Their mathematical model of body cooling was expressed in a two-exponential term. Based on their work a nomogram was developed, which is now the gold standard for determining the time of death.