Thanatology is the science that deals with:

Thanatology refers to a scientific study of death in all its aspects including its cause and phenomena. It also includes bodily changes that accompany death and their medico legal significance. Death occur in two stages: Molecular and Somatic Difference between molecular and somatic death are: Feature Somatic death Molecular death Definition Complete and reversible cessation of function of brain and stoppage of the circulation and respiration Death of individuals cells and tissues Onset Precedes molecular death Succeeds somatic death Response to external stimuli Muscle responds to thermal, electrical or chemical stimulus Does not respond Confirmation Flat ECG and EEG, absent breath sounds Rigor mois, algor mois, postmoem lividity, putrefaction Resemblance Suspended animation, coma, hypothermia Do not resemble any condition Ref: Review of Forensic Medicine and Toxicology By Gautam Biswas page 4.