LATE POSTMORTEM CHANGES/DECOMPOSITION
LATE POSTMORTEM CHANGES/DECOMPOSITION
WILLIAM A. COX, M.D.
FORENSIC PATHOLOGIST/NEUROPATHOLOGIST
November 17, 2009
General Information
The process of postmortem decomposition can be divided into five stages: Fresh (autolysis), putrefaction, black putrefaction, butyric fermentation and dry decay. The first stage begins within minutes of death and last typically up to 36 to 72 hours before the beginning of putrefaction. The length of this first stage, as is true of the entire decomposition process, is primarily determined by environmental temperature. The higher the temperature the faster the decomposition process proceeds through each of the stages. The first stage of decomposition was discussed in the previous article on early postmortem decomposition. This stage included rigor mortis, livor mortis and algor mortis. The underlying process, which initiates the first stage, is autolysis.
Autolysis is the result of molecular changes occurring within the cell, which gives rise to the death of the cell and its subsequent necrosis. This process gives rise to the release of enzymes from the cells, such as the pancreas, and in the case of the stomach also hydrochloric acid.
The pancreas, because of the richness of its enzyme content, provides for digestion of food by secreting more than a liter of digestive juice/24 hours into the digestive tract. Within the digestive juice are enzymes (e.g., amylase, lipase) and precursor enzymes (e.g., trypsinogen), which are responsible for the breakdown of ingested food. Unfortunately, these same enzymes are released from the exocrine cells of the pancreas into itself, which gives rise to autodigestion (autolysis).
The stomach contains a variety of cells, which secrete enzymes and hydrochloric acid that participates in digestion. One of the cells of the stomach are Chief cells, which produce an enzyme pepsinogen. Another cell is the Parietal cell, which, in addition to producing intrinsic factor needed for the intestinal absorption of vitamin B12, also produces hydrochloric acid. Following death both pepsinogen and hydrochloric acid are released from these cells, which gives rise to autodigestion of the gastric mucosa (gastromalacia). If this process is severe enough it can cause perforation of the stomach, typically in the region of the fundus. This same process can also involve the distal ⅓ pf the esophagus due to relaxation of the lower esophageal sphincter following death. This allows for the gastric contents containing the described enzymes and hydrochloric acid to pass into the lumen of the distal esophagus-giving rise to autodigestion (esophagomalacia) of its mucosa and on occasion perforation of its wall. Both gastromalacia and esophagomalacia can give rise to stomach contents leaking into the abdominal cavity and left pleural cavity respectfully. Both can occur within a few hours of death. Although, gastromalacia and esophagomalacia are not common postmortem features, they are seen most frequently in those who have sustained substantive intracranial injuries or have developed terminal pyrexias. These complications have been attributed to an imbalance in the activity of the autonomic nervous system, possibly as a consequence of hypothalamic or brain stem injury.
When the cells of the body reach the end of the autolytic process, an anaerobic environment is created one in which oxygen is no longer present. At this point the body’s normal bacteria begin to break down the tissues further producing acids, gases, and volatile organic compounds with their putrefactive effects.
Putrefaction
Putrefaction is the process by which tissue is destroyed primarily through bacterial proliferation, which occurs soon after death. The bacteria most responsible are those normally found in the respiratory tract and gastrointestinal tract. These bacteria include anaerobic spore forming bacilli, coliform organisms, micrococci, diphtheroids and proteus organisms. The growth of these anaerobic organisms is enhanced due to the increase in hydrogen-ion concentration in the tissues as well as the immediate decrease in oxygen concentration. Between the respiratory and gastrointestinal tracts, it is the latter, which provides the majority of postmortem bacterial growth of which Clostridium welchii is the principal agent. The principal factor, which influences this process, is environmental temperature. Should the deceased have been pyretic prior to death that will also have an effect on the rapidity of development of putrefaction. The optimal temperature for the development of putrefaction is between 70 – 100 ˚F. Putrefaction is retarded below a temperature of 50 ˚F and is hasten by temperature above 100 ˚F.
Putrefaction also occurs faster in those who are obese, have septicemia, congestive heart failure or anasarca, have multiple layers of clothing, hot and humid environments, those dying of cocaine intoxication and those who have sustained traumatic lacerations or incised wounds to the body. Although, warm temperatures hasten putrefaction, very high temperatures will actually delay putrefaction, primarily due to the drying effect on the tissues.
Putrefaction will proceed at a slower rate in cooler temperatures, with freezing suspending the process all-together, in those who are thin, in infants, those who are found in water, those who die in a dry environment, whether cold or warm, those who are found lying on a stone surface and in some cases in which the person has been buried.
In reference to those who have been buried, whether putrefaction is hasten or delayed will be determined by the depth of burial, temperature of the soil, water table, the natural drainage of the burial site and the quality of construction and water tightness of the coffin. If the decedent is buried deep, in well drained soil, especially clay soil, whose coffin is water tight, the process of putrefaction will be substantively delayed. If however, the gravesite is shallow, the soil is moist with poor drainage or the water table is high and the coffin is not water tight the rate of putrefaction will be hastened. However, even without embalming a body buried in a sufficiently dry environment may be well preserved for decades. It is generally agreed that an unembalmed adult buried deep in well drained soil, with a water tight coffin, will be reduce to a skeleton in approximately 10 years, whereas a child will become a skeleton in approximately 5 years. There is a general axiom referred to as “Casper’s dictum” which provides an overall perspective to the putrefaction process, “one week of putrefaction in air is equivalent to two weeks in water, which is equivalent to 8 weeks buried in soil, given the same environmental temperatures.”
The first evidence of putrefaction is the development of a greenish discoloration to the skin usually in the lower right abdominal quadrant, although occasionally you may see it develop simultaneously or initially in the peri-umbilical or left lower abdominal regions. This is typically seen between 36 to 72 hours following death at a temperature of approximately 70 ˚F. The green discoloration is due to the spread of bacteria from the cecum, which lies close to the overlying peritoneal lining in the right lower abdominal quadrant, into the soft tissues. It then spreads from the right lower abdominal quadrant to the remaining abdominal wall followed by involvement of the flanks, chest, limbs and face. The actual green color is due to the bacteria breaking down the hemoglobin of red blood cells (R.B.C) along with the concomitant production of hydrogen sulfide, the net effect of which is sulfhemoglobin. During this process the superficial veins of the skin become visible in an arboressent pattern delineated by a purple-brown coloration. This process is referred to as marblization, which is most commonly seen on the superior aspect of the chest, shoulders, arms and lateral aspect of the trunk. On occasion you may see marblization on the anterior-medial aspect of the thighs. This process is due to the anaerobic bacteria spreading through the veins participating in the hemolysis of the R.B.C., which leads to the staining pattern of marblization, the color being due to hemolyzed R.B.C. reacting with hydrogen sulfide produced by the bacteria. The hemolysis of the R.B.C. will also impart a red color to the endothelial lining of the arteries as well as the endocardium. The time frame that marblization occurs in again is very much temperature dependent. Typically in temperate climates, if the body is exposed to air at temperatures between 64 and 68 ˚F, marblization may appear with in thirty-six to forty-eight hours. It will develop much more rapidly in warmer temperatures.
At this point the skin has taken on a slippery feel and is showing multiple vesicles to frank blisters filled with serous fluid and putrid gases. These vesicles and blisters culminate into skin slippage, with areas of the skin being easily removed from the body with minimal contact. The skin slippage represents the superficial epidermis. The underlying base has a shinny, moist, pink appearance, which if the body is located in a warm dry environment takes on an orange-yellow parchment-like appearance. Along with skin slippage the hair of the scalp, axillae and pubic region is easily removed with minimal pressure.
The skin about the face, neck, upper chest and arms begins to change from a red-green to gray-green, followed by brown-green to purple black color. Gradually this coloration will involve the entire body, however, not necessarily with the same intensity. The entire body will show putrefactive changes in about sixty to seventy-two hours. The change in coloration from green to more of a brown to black hue represents the transition from the early stage of putrefaction to the advanced stage, which is referred to as black putrefaction.
Black Putrefaction
The abdomen at this point is bulging and tense due to putrid gas formation from primarily coliform bacteria and Clostridium welchii both within the gastrointestinal tract and within the abdominal cavity, organs and soft tissues of the chest and abdominal cavities. The putrid gas formation with its concomitant increase in intra abdominal and gastrointestinal luminal pressure leads to purging of putrid, blood-stained fluid from the nose, mouth, vagina and rectum. This same putrid gas formation within the tissue leads to bloating of the body (swelling) in general. The purple-black face swells which also includes swelling of the eyelids and lips, which gives rise to the eyelids being tightly closed and the lips taking on a “fish-mouth-like appearance.” The swollen tongue, often having a purple-black color is seen protruding between the swollen lips. The teeth will often show a red discoloration due to the diffusion of hemoglobin from the lysed R.B.C. into the dentin canaliculi. The swelling of the face and neck can approach grotesqueness, which along with the purple-black color can make identification impossible. The scrotum and penis in the male and the labia majora and breast in the female also exhibit prominent swelling. The gases, which are responsible for this bloating, are comprised of hydrogen sulphide, methane, carbon dioxide, ammonia and hydrogen. These gases, along with the produced mercaptans are responsible for the disagreeable odor these bodies produce.
Typically generalized bloating with purging, skull and hair slippage at a temperature of 70 ˚F occurs between 60 - 72 hours. In addition to the head and body hair becoming loose at their roots and thus being easily removed by minimal pressure, the finger and toenails will at some point become dislodged. Sometime the dislodged finger and toenails will contain much of the epidermis (superficial layer of skin) of the hands and feet, a process called ‘degloving.’ This process of ‘degloving’ occurs at a later time than the loss of either scalp or body hair.
Just as putrefaction affects the external surface of the body so does it involve the internal organs. The stomach and small and large bowel begin to dilate due to various gases being produced by the bacteria within these structures. Both the serosal and mucosal surfaces assume a brown-deep red to purple color. The normal rugal folds become flat. The mucosa of the larynx, trachea and especially the bronchial tree take on a deep-red color; the lumen of the bronchial tree often contains thin reddish-black fluid. The endothelial lining of the major vessels as well as the endocardial surface of the heart has a reddish hue due to hemolysis of R.B.C., thus releasing hemoglobin, which stains these surfaces. On a rare occasion you may see white granules measuring approximately 1 mm in diameter on the surface of the epicardium as well as the endocardium. These white granules are referred to as ‘miliary plaques’ and are believed to be the result of a degenerative process of the cardiac muscle. These ‘miliary plaques’ are rich in calcium. The heart becomes soft and flabby, giving rise to dilatation of the cardiac chambers and thinning of the chamber walls. They myocardium takes on a deep red-brown color. Although, these postmortem decomposition changes make diagnosing antemortem dilated cardiomyopathy virtually impossible, thrombi within the epicardial coronary arteries can still be ascertained. Thus, it is important you dissect the coronary vasculature.
The liver and kidneys assume a deep reddish-brown color with the parenchyma of both organs losing consistency, most especially the liver. As the decomposition process continues the liver shows a myriad of minute cysts, which develops into a honeycomb pattern due to bacterial production of various gases. Bile within the gallbladder diffuses through the degenerating wall staining the adjacent liver, transverse colon and duodenum an olive green color. The adrenal glands quickly undergo autolysis, as does the pancreas. Decomposition fluid, which has a dirty-red color, accumulates in the pleural and abdominal cavities. The chest and abdominal wall panniculus as well as the perirenal, omental and mesenteric fat becomes very slippery, giving rise to a translucent yellow fluid, which also seeps into the body cavities. Organs such as the prostate and uterus remain well preserved even up to a point where the body is partially skeletal zed. The lungs take on a deep red-black color, losing their elasticity, becoming very friable. As they degenerate they exude a dirty red fluid into the pleural cavities.
The brain takes on a gray-white color and a soft consistency, which contains multiple cyst-like cavities throughout its deep white and gray matter. These cyst-like cavities are referred to as ‘swiss-cheese artifact.’ As the decomposition process continues the brain becomes putty-like and eventually liquefies. At some point the maggots will completely consume the entire liquefied brain. However, epidural, subdural and subarachnoid hemorrhage as well as intrparenchymal hemorrhage can often be identified up to the semiliquid (putty-like) state. Neoplastic lesions involving the gray and/or white matter lose their consistency quickly. However, meningiomas and sarcomatous lesions arising from the meningies, because of their fibrous nature can be identified for a far longer period of time.
As the decomposition process proceeds in the black putrefaction stage, both on the external surface as well as within the body cavities, the thoracic and abdominal walls eventually degenerate to the point the contents of the pleural and abdominal cavities are exposed. This process reached this point in the black putrefaction stage not only as the result of bacterial action but also as the result of insect activity, especially in the form of maggots and predators. Before continuing with a general overview of insect and predator activity and their contribution to decomposition I would like to discuss the final two phases of the decomposition process, Butyric fermentation and Dry decay.
Butyric fermentation
The butyric fermentation phase typically begins around the 20th to 25th day following death with the actual time being determined primarily by the environmental temperature. During the black putrefaction stage the bloating begins to subside and the body begins to flattened due to the breakdown of the tissues and the release of the fluid of decomposition and gases as the thoracic and abdominal walls disintegrate as well as consumption by insect and predator activity. In the butyric fermentations stage the body finishes flattening out as the flesh and fluids of the body are consumed and or dry up. Remnants of the more fibrous or muscular organs, such as the heart, prostate and uterus may still be found. It is during this process that butyric acid is produced, which has a very distinct “cheesy” smell. This “cheesy” smell attracts new organisms to the body. The maggots and other insects that feed on soft tissue are unable to feed on a body that is drying out, however, beetles and other insects with chewing mouth appendages are able to chew the tougher drying out tissues of the body. Early in this stage most of the beetles seen are in the larval stage. Hide Beetles from the family Trogidae and Carcass Beetles from the family Dermestidae are among the last beetles and generally the most common beetles seen during this stage. The Hide Beetles and the Carcass Beetles are found on the tougher portions of the body such as bone and ligaments. This is not only due to their chewing mouth appendages but also they are the only beetles that have an enzyme which can break down proteins such as keratin. Although maggots cannot feed on these tough tissues there is a fly that is attracted to the body due to the “cheesy” smell, which is called the cheese fly from the family Piophilidae.
Dry decay
This is the final stage in the decomposition process. It typically begins between 25 and 50 days after death and can last up to a year, again depending on environmental temperature. The only remnants of the body are dry skin, hair, and bones. Mummification, which will be discussed later in this article, may be seen due to the dehydration process in environments, which are typically of dry heat or low humidity. Such mummified bodies can last for decades. The bones go through a process referred to as diagenesis that changes the organic to inorganic constituent ration within the bones. As the protein-mineral bond weakens, the organic protein begins to leach away, leaving behind only the mineral composition. Unlike soft-tissue decomposition, which is influenced mainly by temperature and oxygen levels; the process of bone breakdown is more highly dependent on soil type and pH, along with the presence of groundwater. However, temperature can be a contributing factor, as higher temperature leads the protein in bones to break down more rapidly. If buried, remains decay faster in acidic-based soils rather than alkaline. Bones left in areas of high moisture content also decay at a faster rate. The water leaches out skeletal minerals, which corrodes the bone, and leads to bone disintegration.
Bacteria are also present, feeding on the hair and skin of the body, attracting many mites. Certain tineid moths can also be found feeding on the remaining hair. Silphidae, a family of carrion beetles, may still be present during this stage as well as those of the family Nitidulidae. At this stage, these beetles they are not only feeding on the remnants of dried skin and hair but also the larvae of other insects.
Decomposition and insects
If the process of putrefaction is occurring other than in the winter months and the body is exposed to insects, they will also contribute to the breakdown of the tissues. This is especially true of maggots which give rise to abundant perforations of the chest and abdominal wall with leading to a breakdown of both with exposure of the internal organs.
Each stage of decomposition will have certain insects involved. This will be from flies through to beetles and finally moths as indicated above. The blowflies are the first to find the body and lay eggs. Then come the houseflies and flesh flies.
Blowflies are referred to as carrion flies, bluebottles, greenbottles, or cluster flies. They are insects of the Order Diptera, family Calliphoridae. The female greenbottles (Lucilia cuprina in the United States) is generally the first to colonize the body; the second is the Hairy Maggot Blowfly, Chrysomya rufifacies. Other fly families generally present during this stage are Sarcophagidae, Piophilidae, and Muscidae.
The females of the family Calliphoridae are attracted to carrion both for protein and egg laying, laying from 150 to 200 eggs per patch. Hatching from an egg to the first larval stage takes about 8 hours to 24 hours. Larvae have three stages of development (called instars); each stage is separated by a molting event. The larvae have proteolytic enzymes, which they use to breakdown proteins of the body they are feeding on. At a temperature of 86 ˚F the black blowfly (Phormia regina) can go from egg to pupa in 6 to 11 days. When the third stage is completed the pupa will leave the body and burrow into the ground, emerging as an adult 7 to 14 days later. The rate at which blowflies grow and develop is highly dependent on the environmental temperature and species. There are some 1100 known species of blowflies.
The housefly (Musca domestica) is of the Order Diptera of the Brachycera suborder. It is the most common of all flies found in homes. Each female fly can lay approximately 75 to 150 eggs in each batch. Within a day, the larvae (maggots) hatch from the eggs; they live and feed in decaying organic material, such a dead bodies as well as garbage, feces, open sores, and sputum. The larvae live about one week. At the end of their third instar, the maggots seek a dry cool place where they transform into pupae. The adult flies then emerge from the pupae.
In the life of an insect the pupal stage follows the larval stage and precedes adulthood (imago). The pupal stage is found only in holometabolous insects, that is those insects that undergo a complete metamorphosis, going through four life stages: embryo, larva, pupa and adults (imago). It is during the pupal stage that the adult structures of the insect are formed while the larval structures are broken down. Pupae are inactive, and usually are not able to move.
The flesh flies are of the Order Diptera, family Sacrophagidae. Most breed in carrion, fecal matter, or decaying organic material. A few of species can lay their eggs in open sores. Their larvae (maggots) live for about 5 to 10 days, before descending into the soil and maturing into adulthood. Adults live for 5 to 7 days.
In addition to the flies the beetles (Order Coleoptera) enter the picture, where they feed on the maggots as well as the body itself. Beetles have no specific time that they make their appearance. For example, Staphylinidae may arrive within a few hours after death and remain active into the later stages of decomposition. The Silphidae (carrion beetles) are found in the early stages of putrefaction remaining both as adults and immature forms until the dry stage of decomposition, which depending of the environmental temperature and moisture can be anywhere from 50 to 365 days after death. The skin beetles (Dermestidae) typically arrive at the beginning of the dry stage of decomposition. These bettles feed primarily on dried skin and remaining tissues both as adults and larvae. On occasion you may see species of the checkered beetle (Cleridae), which feed on the Dermestidae. Tineid moths and bacteria eventually eat the person’s hair, leaving nothing but bones.
There are also other insects involved in the decomposition process that can have a substantive influence on the rate of the decomposition process; these belong to the Orders Hemiptera (true bugs) and Hymenoptera (ants, bees, and wasps). Ants can significantly effect decomposition by feeding on the maggots, thus decreasing the rate of decomposition. Wasps also feed on adult flies as well as their larvae. There are certain families of the Order Hymenoptera, which are parasites of larvae and pupae of Diptera, Coleoptera, and other insects, the actions of which retard the decomposition process. True bugs also feed on maggots, thus decreasing their numbers and consequently retarding decomposition.
Fundamental knowledge of entomology can provide invaluable insight into not only when the deceased died but also where and if the body had been moved following death. For example the time of year the deceased died can be determined because certain species of insects are only active at certain times of the year. As an example the bluebottle flies, Calliphora vician, is more abundant during the cooler parts of the year, whereas the greenbottle fly, Phaenicia sericata dominates corpses during the warmest parts of the summer. This determination can be made from insect remains or empty pupal cases of adult flies; thus, depending upon the time of year you will see different grouping of insects. The geographic origin can be determined because many insects are localized to certain localities due to climatic conditions. A specific locality can also be determined based on the fat that certain species of insects are found only in specific locations. As an example, it is possible to determine whether the deceased had been moved from an urban to rural environment following death based upon the fly species present on the body. Altering of the decomposition process may suggest movement or storage of the remains. The decomposition process can be altered if the body is wrapped or stored following death such that it is not exposed to flies. Although the body will continue to decompose due to bacterial action it will reach a point were if it is moved to another location the first blowflies will not lay their eggs due to the stage of decomposition. Also certain species of blowflies only lay their eggs in dark places (Calliphora, bluebottle flies), whereas
Lucilia, greenbottle flies, prefer to lay eggs in well-lit environments.
There is one species of fly that can be seen on buried bodies, called the Coffin Fly, Megaselia scalaris. This fly has the ability to dig up to six feet underground to reach a body and oviposit.
Maggots tend to congregate in traumatic areas, such as lacerations, incised wounds, gunshot wounds, stab wounds, etc. Thus, the maggots in a traumatized area may actually be of an older age than those in the non-traumatized area. This can be very helpful if there is heavy maggot infestation in the genital area. Sampling those maggots with those from other areas of the body may be of some help in determining the existence of trauma. You need to be careful in your interpretation here due to the fact flies tend to lay their eggs first in body orifices.
If you see heavy maggot infestation on one of the hands, this is suggestive of a traumatic injury. Typically the hands become mummified during the decomposition process, hence adult flies would not find them a suitable place to lay their eggs.
It is important to remember that under certain circumstances maggots can be found in those who are still living. As an example, maggots can be found in decubitae (skin ulcers) of those in nursing homes who are not properly looked after. Maggots can also be found in the diapers of infants who are neglected.
Summation of decomposition
How long this process takes is dependent on the environmental temperature, location of the body, time of year and whether insects and or predators have access to the body. If the deceased dies in the summer months, most especially in the south, such as Texas, and is located where insects and predators have ready access to the body, this entire process can occur within days, often less than 2 weeks. If however, the death occurs in the fall the process may take several months not becoming skeletalized until the following spring. In the more temperate climates the process is much slower with skeletalized remains including attached fragments of skin and tendonous tissue taking as long as 12 to 18 months. Skeletal remains without any evidence of attached tissue may take up to 3 years. What is important to remember the time frame in which a body undergoes decomposition and ultimately becomes a skeleton is extremely variable.
There are two variants of the putrefaction process, adipocere and mummification.
Adipocere
Adipocere is a variant of the putrefaction process characterized by hydrolysis and degeneration of unsaturated body fat (adipose tissue) into a yellowish-white, waxy substance consisting of saturated fatty acids. In essence the hydrolysis and hydrogenation of the bodies fat is a form of decomposition specific to the adipocytes (fat cells) and their contained lipids.
Adipocytes are rich in glycerol molecules and are formed by triglycerols (or triglycerides). When these cells are exposed to damp, warm, anaerobic environment, which has undergone invasion by Clostridium welchii, the process of adipocere formation will commence. Although it was once thought that adipocere required either damp conditions or the immersion of the boy in water, it is now know that the water content of the body may be sufficient in of itself to give rise to adipocere even in bodies buried in well sealed coffins. In one study over half the occupants of dry vaults had some adipocere. It was present in 63% of women and 45% of men.
For the process of adipocere formation to take place the invasion of the adipose tissue by endogenous bacteria, of which Clostridium welchii is the principal organ is absolutely essential. Clostridium produces and enzyme lecithinase, which breaks down the triglycerides into saturated and unsaturated, free fatty acids, a process referred to as hydrolysis. In the presence of enough water and enzymes, triglycerol hydrolysis will proceed until all molecules are reduced to free fatty acids. Normally the non-decomposed body contains approximately 0.5% free fatty acid. However, with adipocere formation the percentage of free fatty acid may reach as high as 70% or higher. The unsaturated free fatty acids, such as palmitoleic and linoleic acids, react with hydrogen to form hydroxystearic, hydroxypalmitic acids and other stearic compounds, a process know as saponification, or turning into soap. This final product is referred to, as adipocere is stable for long periods of time due to its substantive resistance to bacterial action. Also, adipocere formation due to the increase acidity of the tissues as well as dehydration due to the loss of water in hydrolysis inhibits the endogenous bacteria thus slowing down the putrefaction process.
Adipocere typically develops in the subcutaneous tissues of the orbits, cheeks, breasts, abdominal wall and buttocks first. There are also occasions where it will involve the internal organs, most especially the liver. The time frame in which adipocere develops is quite variable, with the foundation of the variability being based on the environmental conditions, i.e., a warm, moist, anaerobic environment favoring adipocere formation. Adipocere can be seen in as early as 2 weeks, though usually it requires 1 to 2 months to be substantive and as long as 5 to 6 months for completion. In a closed vault it can persist for centuries. In its early formation it gives rise to an ammonia-like odor, some describing it as earthy. Later on in its development it has a rancid sweetness.
One of the points you need to keep in mind is if the body is exposed to insects, adipocere formation may not occur due to the fact the putrefactive process will proceed at a much faster rate due to the insect activity (i.e., maggots, etc.). Also predators feeding on the body will also prevent adipocere formation.
Adipocere is often admixed with other forms of decomposition most notably mummification or parts of the body will be skeletalized.
Mummification
Mummification is a modification of putrefaction due to dehydration and desiccation of the tissues. It typically occurs within a dry environment (low humidity), one with high temperatures and movement of air. However, there is a form of peripheral mummification, which is seen quite commonly in the early stages of decomposition, in which the trunk is beginning to show in early green coloration in the lower right abdominal quadrant. Examination of the distal extremities, especially the fingers and toes will show a black coloration with evidence of desiccation of the tissues and skin assuming a leather-like appearance. This drying effect can also be seen involving the skin of the scrotum in which it takes on a brown parchment-like appearance. These changes are typically seen between 48 to 72 hours in those dying in temperate climates, with a temperature of approximately 70 ˚F. The process we are interested in is one more of central or diffuse mummification of the body.
The process of mummification typically occurs in a hot, dry environment, one with air circulation, it can also occur in refrigerated or freezing-like conditions. This is primarily due to the low humidity and the inhibition of bacterial action.
The process of mummification is rarely seen in adults with the exception of those who die in geographical localities that are constantly hot and dry, such as in the southwestern United States and the Sahara of North Africa. There are other microenvironments in which it can occur such as a death in a vehicle, in which the windows are closed with the death occurring in the winter. The cold temperatures would retard the endogenous bacteria and do to the dryness of the air the body would have a shriveled-like appearance covered with brown parchment-like skin, with the extremities being more severely involved then the trunk.
There is an important point to remember and that is the skin shrinkage can actually produce linear defects in the skin, which can mimic incised wounds or lacerations. These are typically seen around the neck, groin and armpits.
The internal organs will also show evidence of mummification manifested by prominent shriveling. They typically will have a black coloration and a leather-like consistency.
Mummification, although uncommon in adults, is quite common in newborn infants and fetuses. This is due to the fact they have little if any endogenous bacteria within the intestines, hence the usual decomposition process is markedly inhibited. Also, due to their large surface area relative to their body mass dehydration occurs much faster and is far more complete than in the adult.
The time required for complete mummification of the body is difficult to ascertain due to the variability under the conditions it occurs as well as the lack of definitive knowledge in knowing how long the body was exposed to these environmental conditions; clearly it requires several weeks, especially in ideal conditions.
Postmortem changes in buried bodies
In general the decomposition process is slower when the body is buried, whether in or not in a coffin, as compared to air or water. The degree of putrefaction of buried bodies is determined by a number of factors: degree of decomposition before burial, environmental temperature, whether insects or animals had access to the body before burial, lack of oxygen, depth of the burial, type of soil and whether buried in a coffin or not.
If the body is buried before postmortem decomposition takes place, putrefaction if it occurs, will do so at a much slower rate and may never reach the stage of black putrefaction. This is especially true of a body buried deep in clay soil, but well above the water table. Sandy soil will allow more oxygen and water to reach the body enhancing decomposition. However, if it has good drainage, this feature may partially offset the increase exposure to water.
If decomposition has already started before burial, it will continue after burial, the rate being principally determined by environmental temperature, shallowness of the grave, soil type and water table.
Lower environmental temperatures, as previously discussed, will in of itself retard decomposition. If animals and insects, such as flies, do not have access to the body than their enhancement of decomposition such as through maggot activity will not take place. There is however an exception, the Coffin Fly, Megaselia scalaris, is one of the few fly species seen on buried bodies because it has the ability to dig up to six feet underground to reach a body and oviposit.
Although, the initiation of the decomposition process is due to endogenous bacteria within the intestines, which are anaerobic, with Clostridium welchii being the principal organism, aerobic bacteria also play a role. Lack of oxygen would thus decrease their participation.
In regard to coffins, their ability to retard decomposition is determined by the quality and types of materials used in their construction, whether they are water tight, and the water table and or drainage of the soil. A coffin made of wood laminate or chipboard will disintegrate rapidly when exposed to water. In contradistinction, a watertight metal coffin will maintain the body in an excellent state of preservation, especially if they have been embalmed well.
Postmortem changes in bodies buried in moist environments
As previously discussed, Casper’s law indicates a body will decompose twice as fast in air than water and eight times faster than those who are buried. Casper’ law should be interpreted in a general sense. In essence, what it is trying to indicate is that bodies in water will decompose at a slower rate due primarily to the lower environmental temperature as well as denying insects and animal predators access to the body. Having said that, bodies that have been in the water, even for a brief period of time, may show the effects of fish, crab, and shrimp activity. These effects are typically noted on the eyelids, lips, tip of the nose and earlobes. Also, any exposed skin may show evidence their activity.
The type of water the body is immersed in also makes a difference. Bodies immersed in seawater decompose at a slower rate than those in fresh water; this is due to the salinity of seawater, which retards bacterial growth. If the body is immersed in stagnant water, the decomposition process will proceed at a rapid rate due to the high bacterial content.
Whether a body is found on the surface of the water or found below the surface is dependent on the salinity of the water, fat content of the body, temperature of the water, and whether putrefaction has occurred with gas formation.
Bodies found in seawater will not uncommonly be found on the surface. In fresh water bodies will usually sink towards the bottom, resurfacing, due to gas formation within the body due to putrefaction. In general, it is the temperature of the water, which determines how fast a body resurfaces. In the warmth of a temperate zone summer, a body may rise to the surface within two to three days in a lake or pond. If a body sinks in seawater under the same conditions it may take two to three weeks to resurface. However, if the water is cold the body may not resurface for weeks to months. If the water is very cold, near freezing, it may never resurface.
Another factor that effects how soon a body will resurface is its habitus; obese bodies tend to rise sooner than lean ones.
Bodies that resurface are usually found floating face down due to the fact of the relative density of the head as compared to the rest of the body and also that it does not develop early gas formation that occurs in the abdomen and thorax.
Other forms of decomposition can also be seen in bodies found in water. Mummification can be found in those parts of the body not immersed and exposed to the air. Adipocere can also be found in immersed bodies, especially those immersed in warm water. Adipocere usually requires immersion in water for several months, although it can form in a matter of weeks in warm water. This is primarily due to warm waters less oxygen content as compared to cold water and its enhancement of bacterial growth. Fungi can also be found in bodies immersed in water or found in a moist environment.
On occasion bodies can be found in a unique wet environment referred to as a bog. A bog is a wetland that is formed through the accumulation of acidic ground water and deposits of dead plant material, typically mosses. The water in a bog has a brown color due to the dissolved peat tannins. This coloration is imparted to the immersed bodies. Due to the bogs natural anaerobic environment and the presence of tannic acids they serve as an excellent medium for preservation of organic materials including human remains. It is not uncommon for bogs to preserve bodies with the internal organs, skin and hair all intact for thousands of years.
Maceration
Maceration is the aseptic autolysis of a fetus, which has died in utero and remained within the closed amniotic sac. Intrauterine maceration must be distinguished from decomposition due to the fact that in most instances decomposition is indicative of a live birth whereas maceration indicates stillborn.
The changes of maceration occur quickly in an intrauterine death, with skin slippage, which is due to separation of the epidermis from the underlying dermis, occurring as early as 6 hours of death and most definitely within 12 hours. With slippage of the epidermis from the dermis, the dermis takes on a red color. If the fetus is retained in utero for 7 to 10 days the red color changes to a purple to brown hue. After several weeks in utero the deceased fetus will take on a yellow-gray color.
Typically within 2 to 3 days of death in utero the fetus will lose firmness of its tissues, which manifest by a generalized softness on palpation. This is due to autolysis of its tissues. At the 7 to 10 day mark the skin has a slimy-like feel. The limbs are very loose, which in some cases will easily separate from the trunk. The prominent over-lapping of the bones of the calvarium gives the skull a misshapen appearance. The fetus will often have a rancid odor but there will be no gas formation.
The organs most severely affected by autolysis in macerated stillbirths are usually those in the abdominal cavity, i.e., the pancreas, liver, spleen and adrenal glands. It is the presence of abundant protolytic enzymes in the pancreas and liver which gives rise to their rapid autolysis. The other organ, which undergoes rapid autolysis, is the brain, which is primarily due to its high water content. However, even if the brain is in a semi-liquid state, the cerebral hemispheres will retain their normal convolutional pattern; hence the gyration formation may aid you in the determination of gestational age. Another factor to keep in mind when determining gestational age is that autolysis of the connective tissue may allow for stretching of the fetus, thus increasing the crown-rump and crown-heel lengths. However, the foot and hand lengths are typically minimally altered. Also, the overlapping of the cranial vault bones, although making head circumference measurements difficult, if done carefully, and used in conjunction with cerebral cortical gyral formation and foot and or hand lengths, may give you a reasonably accurate gestational age.
In rare instances, typically in multiple pregnancies, one of the fetuses will die. Their death is followed by a progressive loss of fluid from the tissues and organs, which leads to shrinkage and compaction. This ultimately culminates in the fetus becoming flattened due to mechanical compression in the womb, assuming the appearance of parchment-like paper. The process is referred to as “fetus papyraceus.” There are also rare cases in which an extrauterine pregnancy is retained within the mother’s abdomen for years, with the fetus becoming calcified (Lithopedion).
There are occasions, however, in which the putrefaction process will override the maceration process. As an example, should the amniotic membranes rupture, but the deceased fetus is retained in the uterus for any length of time, it will be exposed to the endogenous bacteria in the cervix and vagina, thus giving rise to decomposition. Also, should the intact amniotic membranes become involved with chorioamnionitis, the fetus will be exposed to the causative bacteria, which in turn would give rise to decomposition. The reason this is of great importance is any degree of decomposition will make it virtually impossible to determine, whether a live birth took place.
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