After Rigor Mortis, Livor Mortis, and Algor Mortis, decomposition is the fourth sign of death. The length of time it takes for a substance to decompose varies greatly depending on the climate. In comparison to a northern climate, where the same amount of decomposition could take a week or longer, hot, subtropical areas can produce advanced decomposition in as little as 24 hours. When a musty, rancid odour appears, decomposition begins. The odour comes from autolysis and putrefaction processes, and the changes are mostly caused by bacteria in the body breaking down tissue. Decompositional changes then progress to skeletonization, starting with a greenish discoloration of the abdomen.
The following is a timeline of the changes:
1. The first sign is a greenish discoloration of the abdomen, which spreads to the rest of the body.
2. As the body discolours, it swells due to bacterial gas formation, which is accelerated in warm weather and slowed in cold weather. The eyes and tongue protrude as the tissues swell.
3. As the body bloats, the epidermis slips and blisters form, and the blood begins to deteriorate.
3. Blood degradation causes “venous marbling,” in which hemolyzed blood “tattoos” the tissues, leaving blood vessel outlines.
4. The process of purging begins. Decomposed blood and body fluids emerge from body orifices, appearing dark brown and smelling foul, owing to gas propelling the fluid along the path of least resistance.
5. Finally, depending on the environment, skeletonization can take weeks or months. Many bodies have been discovered partially skeletonized.
6. Exposed body parts decompose more rapidly. The visceral part of the body also decomposes quite pretty fast (i.e., the abdomen, chest, and head). When a body part is exposed due to an injury, it decomposes more speedily. This decomposition is accelerated by insect activity.
7. Temperature, humidity, insect activity, and the state of the body at death all influence decomposition. Patients with infections, for example, may decompose more quickly.
8. Insects, carnivores, and other invaders can hasten the process of decomposition. The study of insects in relation to death investigation is known as forensic entomology. Fly larvae, for example, can be collected at the scene of a death, identified, and reared in incubators.
The postmortem interval (time of death) can be calculated using the fly larvae’s fixed-time growth cycles.
9. When a body found in water is removed, the “gas bloating” can be quite impressive.
10. Environmental conditions have a big impact on decomposition. Freeze-dried bodies can be kept for a long time. Because cold temperatures preserve tissues, bodies are kept in a morgue cooler at 38°F–42°F, where decomposition is slowed for days to weeks. Warm temperatures, as well as high humidity, hasten decomposition. Mummification, or the drying out of tissues, is caused by hot, dry conditions.
Other Decompositional Changes
Adipocere is also known as corpse wax, grave wax or mortuary wax.
It appears most evidently on the face, cheeks, breasts, belly, and buttocks, where fat is abundant. Limbs, the chest wall, and other body regions are less affected.
In moist environments, fat tissue beneath the skin begins to saponify (turn into a soapy substance). It takes at least a few weeks for a hard, wax-like material to form, which keeps the body in a relatively preserved state for many months. There is no green discoloration or significant bloating, unlike with normal decompositional changes. The skin on the outside of the body remains white to brown, and the outermost layers of skin peel off.
Adipocere will be evenly distributed over all body surfaces in bodies that are completely submerged in cold water.
Mummification is a kind of putrefaction in which the skin becomes brittle, constricted, dry, stiff, leathery rough, parchment-like, shrunken, and wrinkled, and the colour changes from yellow-brown to black.
Mummification takes place in hot, dry environments. Bacterial proliferation may be minimal as the body dehydrates. The skin darkens, dries out, and becomes leathery. In dry environments, regardless of temperature, the process occurs easily in the fingers and toes. The majority of mummified bodies are discovered during the summer months or in hot, dry climates. Mummification can occur indoors during the winter, particularly if the heat is turned up, creating a hot, low-humidity environment. In the right conditions, an entire body can mummify in a matter of days to weeks. Once in this state, a body can be preserved for many years.
- Shrestha R, Kanchan T, Krishan K. Methods Of Estimation Of Time Since Death. [Updated 2021 Jul 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549867/
- Jaafar S, Nokes LD. Examination of the eye as a means to determine the early postmortem period: a review of the literature. Forensic Sci Int. 1994 Feb;64(2-3):185-9.
- Van den Oever R. A review of the literature as to the present possibilities and limitations in estimating the time of death. Med Sci Law. 1976 Oct;16(4):269-76.
- Wróblewski B, Ellis M. Eye changes after death. Br J Surg. 1970 Jan;57(1):69-71.
- Bardale RV, Tumram NK, Dixit PG, Deshmukh AY. Evaluation of histologic changes of the skin in postmortem period. Am J Forensic Med Pathol. 2012 Dec;33(4):357-61.
- Babapulle CJ, Jayasundera NP. Cellular changes and time since death. Med Sci Law. 1993 Jul;33(3):213-22.
- Madea B. Methods for determining time of death. Forensic Sci Med Pathol. 2016 Dec;12(4):451-485.
- Nokes LD, Flint T, Williams JH, Knight BH. The application of eight reported temperature-based algorithms to calculate the postmortem interval. Forensic Sci Int. 1992 May;54(2):109-25.
- Henssge C. Death time estimation in case work. I. The rectal temperature time of death nomogram. Forensic Sci Int. 1988 Sep;38(3-4):209-36.
- Henssge C, Madea B. Estimation of the time since death in the early post-mortem period. Forensic Sci Int. 2004 Sep 10;144(2-3):167-75.
- Anders S, Kunz M, Gehl A, Sehner S, Raupach T, Beck-Bornholdt HP. Estimation of the time since death–reconsidering the re-establishment of rigor mortis. Int J Legal Med. 2013 Jan;127(1):127-30.
- BATE-SMITH EC, BENDALL JR. Factors determining the time course of rigor mortis. J Physiol. 1949 Dec 15;110(1-2):47-65.
- Kaatsch HJ, Schmidtke E, Nietsch W. Photometric measurement of pressure-induced blanching of livor mortis as an aid to estimating time of death. Application of a new system for quantifying pressure-induced blanching in lividity. Int J Legal Med. 1994;106(4):209-14.
- Vanezis P. Assessing hypostasis by colorimetry. Forensic Sci Int. 1991 Dec;52(1):1-3.
- Wyler D, Marty W, Bär W. Correlation between the post-mortem cell content of cerebrospinal fluid and time of death. Int J Legal Med. 1994;106(4):194-9.
- Meurs J, Krap T, Duijst W. Evaluation of postmortem biochemical markers: Completeness of data and assessment of implication in the field. Sci Justice. 2019 Mar;59(2):177-180.
- Madea B. Importance of supravitality in forensic medicine. Forensic Sci Int. 1994 Dec 16;69(3):221-41.