Human Body Decomposition

Jarvis Hayman,Marc Oxenham

• Publisher: Academic Press
• Year: 2016
• ISBN:
  9780128037133
• Topic: Jura
• Subtopic: Forensik

The fate of the human body after death is a subject that has fascinated enquirers, both in the scientific and legal realms for millennia. However, objective research into the causes and nature of human decomposition has only taken place in the last two centuries, and quantitative measurement of the process as a means of estimating the time of death has only recently been attempted. The substantial literature concerning this research has been published in numerous scientific journals since the beginning of the nineteenth century. Human Body Decomposition expands on the current literature to include the evolving research on estimating the time of death. This volume details the process of decomposition to include early period after death when the body cools to ambient temperature, and when the body begins to putrefy. This process is significant because the estimation of the time of death becomes increasingly more difficult when the body begins to putrefy. Human Body Decomposition compiles a chronological account of research into the estimation of the time since death in human bodies found decomposed in order that researchers in the subject field can concentrate their thoughts and build on what has been achieved in the past.

• Provides concise details of research, over the last 200 years, of estimating the time of death in decomposed bodies.
• Covers methods of research into human decomposition in the stages of body cooling to ambient temperature and the later stages of autolysis, putrefaction and skeletonisation.
• Includes a detailed account of recent research and future concepts.
• Concludes with an account of the difficulties which future research into human decomposition will encounter.

Chapter 1

Supravital Reactions in the Estimation of the Time Since Death (TSD)

Abstract

The supravital period is the period immediately after cessation of the heart and circulation during which the body remains responsive to certain stimuli. Attempts have been made to measure these stimuli as a means of estimating the time of death. These stimuli are the temporary widespread muscle contraction (rigor mortis), dark discolration caused by deoxygenated blood pooling in dependent tissues (livor mortis), and the waning responsiveness of muscle to mechanical and electrical stimuli. Measurement of these stimuli is not accurate and should not be used alone to estimate the TSD.

Keywords

Time since death; rigor mortis; livor mortis; muscle excitability

Outline

Rigor Mortis

Livor Mortis

Measurement of Mechanical and Electrical Excitability of Muscle

References

Following the cessation of the heart and circulatory system at the moment of death, there is a period of time, generally accepted to be 3–4 minutes after the heart stops beating, during which some tissues remain responsive to various stimuli, and when resuscitation may be possible despite increasing anoxia of the tissues and resultant irreversible ischemia. However, it is not equivalent to the supravital period which is believed to extend from 100 to 120 minutes after cessation of the circulation (Madea, 2002a). During the supravital period, the tissues remain responsive to various electrical and mechanical stimuli and exhibit certain phenomena such as rigor mortis and livor mortis. Attempts have been made to use these reactions and phenomena to measure the time since death (TSD).

Rigor Mortis

The phenomenon of rigor mortis was first described in 1811 by the French physician, P.H. Nysten, but its physiological basis was not discovered until 1945 by Szent-Györgyi (2004). It consists of a sustained contraction of the muscles of the body, which begins at 2–6 hours after death, persists for 24–84 hours, and is then followed by gradual relaxation until the muscles again become flaccid (Gill-King, 1997). The contractile units of muscle cells, sarcomeres, consist of parallel units of two types of protein, actin and myosin. Crosslinkages on the myosin units pull the actin units toward each other, causing muscle contraction. The process requires calcium and energy, the latter provided by adenosine triphosphate (ATP) (Bate-Smith and Bendall, 1947). The initial flaccidity of muscles after death is due to continued formation of ATP by anaerobic glycolysis, but with the passage of time, ATP is no longer resynthesized, energy is no longer available for the actin and myosin fibrils to remain relaxed and the fibrils contract, resulting in the muscle body as a whole contracting. Resolution of rigor mortis after 24–84 hours is caused by proteolytic enzymes within the muscle cells disrupting the myosin/actin units, causing the crosslinkages to break down and the muscles to relax (Gill-King, 1997).

At the beginning of the 19th century Nysten (1811), in France, carried out experiments on criminals immediately after their decapitation on the guillotine and he observed that rigor mortis began in the muscles of the jaw and then progressed distally to the feet and toes. This sequence was disputed by Shapiro (1950, 1954), who suggested that it began at the same time in all muscles but the variation in the sizes of the different joints and muscles meant that the larger muscles took longer to develop rigor mortis, giving the impression that it progressed from proximal to distal in the body. Krompecher designed an experiment to measure the intensity of rigor mortis in rat front limbs compared with rat hind limbs using different forces at different times during the course of rigor mortis (Krompecher and Fryc, 1978a). The hind limbs had a muscle mass 2.89 times the muscle mass of the front limbs. The results showed that although there was no difference between front and hind limbs with respect to the time taken to reach complete evolution of the rigor mortis, the onset and the relaxation of rigor mortis were more rapid in the front limbs which had the smaller muscle mass. In contrast, Kobayashi and colleagues (2001), experimenting with in vitro rat erector spinae muscles, found that although the volume of muscle samples varied there was no difference in the development and resolution of rigor mortis. They concluded that it was the proportion of muscle fiber types in each muscle, difference in temperature, and the dynamic characteristics of each joint that determined the speed of onset and resolution of rigor mortis.

Several intrinsic and extrinsic factors affect the speed of onset and duration of rigor mortis. Intrinsic factors such as violent exercise and high fever during the agonal stage will cause a rapid onset and shorter duration. The amount of skeletal muscle dictates the duration of rigor, for example, it appears and resolves early in infants but, in contrast, a robust physical person will have slower onset and a prolonged duration (Gill-King, 1997). This finding, however, was contradicted by Kobayashi and colleagues (2001). Krompecher and Fryc (1978b), in a study using rats, found that physical exercise before death caused an increased intensity of the rigor which reached its maximum intensity at the same time as normal controls but the maximum intensity was sustained longer. The rigor, however, reached resolution at the same time as the controls. In a controlled experiment using rats, Krompecher (1981) found that the higher the temperature, the shorter was the onset of rigor and the faster the resolution, a finding later confirmed by Kobayashi and colleagues (2001). At very low temperature (6°C), development was very slow at 48–60 hours and resolution very prolonged to 168 hours. This contrasted with a temperature of 37°C when development occurred at 3 hours and resolved at 6 hours. In a mortuary where corpses were kept refrigerated at 4°C, rigor was found to completely persist for 10 days in all corpses, became partial by 17 days, and resolved after 28 days (Varetto and Curto, 2005).

Other extrinsic factors which affect the course of rigor mortis are electrocution causing death, which accelerates the onset of rigor and shortens the duration, possibly because the violent cramps experienced cause a rapid fall in ATP (Krompecher and Bergerioux, 1988). Strychnine poisoning hastens the onset and duration of rigor mortis while carbon monoxide poisoning delays the resolution (Krompecher et al., 1983). If the rigidity of rigor mortis is broken by force it can re-establish itself if the process is still ongoing; the re-establishment begins immediately after being broken, the rigidity is weaker but the maximum extent of it is the same as in controls, as is the course of resolution (Krompecher et al., 2008).

Objective measurement of the force required to break the rigidity of rigor mortis was attempted for many years, the first attempt being made in 1919 by Oppenheim and Wacker, but the difficulty in measuring this force is that the strength of the force varies with the stage of development and resolution of the rigor mortis (Krompecher, 2002). The forces involved are initially small, rising rapidly to a maximum, and then reducing gradually over time until resolution occurs. One measurement at one period of time in the duration of the rigor will not reveal any useful information concerning the estimation of the TSD. Krompecher (1994) carried out experiments on groups of rats killed by a standard method and kept at the same temperature of 24°C post mortem. The same force, insufficient to break the rigor, was applied to a limb at varying intervals after death up to 48 hours. It was found that repeated measurements of the intensity of rigor mortis allowed a more accurate estimation of the TSD than a single measurement and Krompecher suggested certain guidelines: (1) If there was an increase in intensity, the initial measurements were taken no earlier than 5 hours post mortem. (2) If there was a decrease in intensity the initial measurements were taken no earlier than 7 hours post mortem. (3) At 24 hours postmortem resolution was complete and no further change in intensity should occur. A recent study of 79 deceased patients was undertaken in a hospital mortuary where the time of death was known, where they were all transported to the mortuary within 5 hours and kept at a temperature of 20–21°C (Anders et al., 2013). The aims of the study were to determine if re-establishment of rigor mortis took place in loosened joints after more than 8 hours and, if so, could it be determined how many hours postmortem re-establishment of rigor mortis did occur? Deaths occurred from a variety of disease conditions but because of the small numbers, no correction was possible for disease state. Rigor mortis was loosened in 174 joints of 44 deceased persons between 7.5 and 10.5 hours post mortem to determine whether re-establishment occurred after 8 hours and 140 joints were examined after loosening at 15–21 hours post mortem to determine how many hours postmortem re-establishment could occur. The study found that 121 of 314 joints (38.5%) showed re-establishment of rigor mortis between 7.5 and 19 hours and the authors concluded that the currently accepted view that rigor mortis could only be studied to determine the time of death less than 8 hours post mortem, required re-evaluation by further studies. Attempts have been made to standardize the measurement of the force of rigidity in rigor mortis but they have not received widespread acceptance (Schuck et al., 1979; Vain et al., 1992). Because of the subjective nature of the assessment of rigor mortis and the number of variable factors determining its onset, duration, and resolution, it should only be used in conjunction with other methods when estimating TSD (Henssge and Madea, 2002).

Livor Mortis

Livor mortis or lividity is the gravitational pooling of blood in the dependent parts of the body, both externally in the skin capillaries and venules but also in the internal organs. Its onset is variable but it is usually most evident about 2 hours after death, although it is stated to occur as soon as 15 minutes after death (Clark et al., 1997). Initially the color is red but it later becomes purple as oxygen dissociates from the hemoglobin, changing it to purple-colored deoxyhemoglobin. This color change can be variable depending on the circumstances of death and the environment. Cold temperatures will delay the dissociation of oxygen from the hemoglobin, delaying the color change from red to purple. Carbon monoxide poisoning produces a persistent cherry red color and cyanide poisoning will also cause the red color to persist. Lividity may not be seen in bodies that are very anemic at death. Initially it is not fixed, that is, if pressure is applied to a skin area the red color changes to white as the blood is returned to the capillaries due to the pressure. Bodies lying on a hard surface will also show white blanching in the areas making contact with the surface for the same reason. Lividity is said to become fixed in 4–6 hours, that is, the red color no longer disappears on pressure because with cooling of the body, the fat surrounding the capillaries solidifies, constricting the capillaries and preventing the return of blood into them (Clark et al., 1997).

A reference to lividity occurs in the earliest extant comprehensive handbook for mid-13th-century Chinese forensic investigators into homicides and other deaths by Sung Tz’u. A clear description of lividity occurs toward the end of Sung Tz’u’s (1186–1249) handbook: “Generally, dead persons have a slight red coloration on the back of the neck, on the top of the back, on the ribs, the back of the waist, the insides of the legs, the knees, the feet and the stomach. Check to determine if after death these corpses were laid out supine overnight. The collapse of the blood vessels may cause this slight red coloration, which does not indicate any other cause of death.”

Turning to more recent times, the time sequence of livor mortis has been proposed as a method of estimating the TSD. However, the physiological mechanism of blood pooling, coagulation, and hemoglobin dissociation is so variable as to make it an unreliable method (Knight, 2002). The assessment by observation with the passage of time is subjective and therefore prone to observer error. Recently attempts have been made to quantify the hypostasis of lividity by colorimetry. A preliminary study carried out by Vanezis (1991), using a colorimeter, showed a linear relationship between the passage of time and the lightening color intensity when bodies showing lividity in dependent areas were turned over to enable blood to return to capillaries. Hypostasis reduced considerably even after 24 hours and slightly up to 3 days after death. In a follow-up study, Vanezis and Trujillo (1996) attempted to quantify the rate of change in the intensity of livor mortis with time by the use of a colorimeter. Ninety-three cadavers in whom the time of death was known to within 3 hours were subjected to colorimetric study. The bodies, kept at 4°C, were placed in the prone position and the degree of luminosity on their backs measured at 4-hourly intervals up to 72 hours. A strong correlation was found between the degree of luminosity and the postmortem interval (PMI), lividity becoming darker with increasing PMI in an exponential fashion. After 72 hou...