Post-mortem interval (PMI) refers to the time elapsed between the death of a person or animal and the commencement of an autopsy or examination. Synonyms for PMI include death-to-dissection interval, time-to-autopsy, and post-death interval. Other terms that are used in forensic science to refer to PMI are post-mortem changes, post-mortem aging, and cadaveric decomposition. These expressions describe the various physical and biological changes that occur to a deceased body over time. Forensic pathologists use these changes to estimate the time of death and establish a timeline of events leading up to it. PMI is critical for solving a range of criminal cases from homicides to accidental deaths.