Post-mortem interval (PMI) is the time that has elapsed since a person has died. If the time in question is not known, a number of medical/scientific techniques are used to determine it. This also can refer to the stage of decomposition of the body.
Types of change after deathEdit
- Algor mortis - body cooling;:16
- Livor mortis - settling of blood in the lowest-placed parts of the body;:15–16
- Rigor mortis - stiffening of limbs;:115
- Forensic entomology - insect (especially blowfly):2 activity on the corpse;:17
- Vitreous humour changes - eye chemistry;
- State of decomposition - autolysis (process of self digestion) and putrefaction (process caused by bacteria found within the body).:16
Traditional decomposition stagesEdit
A person who judges the time of death by the means of decomposition can refer to a simple five-stage process:
- Stage 1: Initial Decay - Bacteria located mainly in the lower intestine begin decomposition, giving a greenish color to the lower abdomen.:17
- Stage 2: Putrefaction - Bacteria grow throughout the body, releasing gases, including cadaverine, which in turn bloat the body and cause unpleasant odor.
- Stage 3: Black Putrefaction - This stage brings further discoloration to the body. The gases from bacterial decay begin to escape, causing strong odor.
- Stage 4: Butyric Fermentation - The internal organs liquefy and the body begins to dry out.
- Stage 5: Mummification - This is the slowest of the five stages. In a hot, dry climate the body may dehydrate, inhibiting bacterial decay; the skin dries to a dark leathery appearance.:17
More advanced methodsEdit
More advanced methods include DNA quantification, infrared spectroscopy. and for buried individuals changes in soils such as the levels of methane, phosphates and nitrates, ninhydrin-reactive nitrogen, volatile organic compounds and water conductivity.
- Survey of Biological Factors Affecting the Determination of the Postmortem Interval. Bautista, Richard. Spring 2012.
- Blood, guts, gore and soil: decomposition processes in graves and forensic taphonomic applications. Tibbett, Mark. 2010 19th World Congress of Soil Science, Soil Solutions for a Changing World.
- Zilg, B.; Bernard, S.; Alkass, K.; Berg, S.; Druid, H. (17 July 2015). "A new model for the estimation of time of death from vitreous potassium levels corrected for age and temperature". Forensic Science International. 254: 158–166. doi:10.1016/j.forsciint.2015.07.020.
- Kokavec, Jan; Min, San H.; Tan, Mei H.; Gilhotra, Jagjit S.; Newland, Henry S.; Durkin, Shane R.; Casson, Robert J. (19 March 2016). "Antemortem vitreous potassium may strengthen postmortem interval estimates". Forensic Science International. 263: e18. doi:10.1016/j.forsciint.2016.03.027.
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