I’m sure most of us agree that Death is an inevitable part of life. Similarly, the events that occur in the body following the individual’s death is also inescapable. Have you ever wondered how our body would change after our death? This article aims to give you an understanding of death, in a biological sense, and the various stages that are associated with death.

There is no known legal definition of death. From a medical or biological point of view, Death is characterized by an irreversible & permanent loss of vital functions which causes cessation of life. Following an individual’s death, there is a certain specific sequence of events that occur in the body as a part of a natural phenomenon, which ensures that the body is decomposed and restored to the earth. Thus, we can say that “Death is a part of life, and decomposition is a part of death.” (Postmortem Changes, 2020)

The term “Post-Mortem” is used to refer to the ‘events that occur after Death’. Similarly, ‘Post-mortem changes’ refers to the changes that occur in the body after an individual dies. This is when Forensic Medicine comes into the picture, where it plays an important role in determining an individual’s manner of death, especially in the cases where the person has died under suspicious circumstances. 

 “Forensic Thanatology is also known as ‘the scientific study of death’. This is an area of Forensic Medicine that investigates the mechanisms and forensic aspects related to death, which include the bodily changes that accompany death and the post-mortem period. (Forensic Thanatology | List of High Impact Articles | PPts | Journals | Videos, n.d.)

During a forensic investigation, the study and interpretation of the post-mortem changes that occur in the body is an essential aspect to estimate the time since death, which is also known as ‘Post-mortem Interval’ (PMI). 

When an individual dies, the estimation of the PMI will help us get an understanding of how long before the person had died, by the time their body was discovered. This can act as an important lead for the investigation into the person’s death. 

For instance, when dealing with cases of homicide, if the investigators know the approximate time around which the victim had been killed, it may be helpful to question the suspect regarding their whereabouts during the estimated time of the victim’s death. (Wardak & Cina, 2011)

Sometimes, the identification of death becomes tricky when there is no apparent cause of death. For example, when a person is found unconscious, with no apparent evidence of injuries, commonly encountered in cases of cardiac arrest, drug overdose, and sometimes even in cases of drowning, it becomes difficult to determine for certain whether the person is dead or in a state of coma. In such cases, it is always necessary for the victim to be first examined by a medical officer before being declared dead. (Sharma, 2014)

Bodily changes after death:

As mentioned earlier, following our death, several changes occur in our body. This occurs as a result of complex physicochemical activities occurring in the body as well as the external environmental factors that affect the body. These bodily changes occur in an orderly manner, and this is what helps the forensic investigators to estimate the time since death (Post-mortem Interval). 

Stages of Death:

In a biological sense, death is said to occur in two stages. The first being the “Somatic Death”, which is also known as “Systemic Death”. This is followed by the second stage, which is called as the “Molecular Death” or “Cellular Death”. (Reddy & Murty, 2014)

The signs of death appear in the order as stated below.  

1. Somatic Death (Systemic Death):

• This characterized by the complete and irreversible loss of vital functions of the body. This includes the cessation of the Heart, Lungs and the Brain. These three vital organs together are known as the “Bishop’s Tripod of Life”.
• Somatic death can be tested by the withdrawal of any artificial life support systems such the ventilator, artificial pacemakers, internal defibrillators, dialysis machines, etc.
• It must be understood that it takes some time for the vital organs to completely cease functioning. Therefore, at this stage, the cells and tissues in the body are still alive.

2. Molecular Death (Cellular Death): 

• During this stage, sequential death of the cells and tissues in our body occurs.
• This stage starts 1-2 hours after the cessation of the function of the vital organs.
• The cells begin to die as the anaerobic processes stop, due to the non-availability of Adenosine Triphosphate (ATP), which acts as the main source of energy for most cellular processes. 

Signs of Immediate Post- Mortem Interval (PMI) in the body 

Once the stage of molecular death begins, there will be visible changes on the external surface of the body. These can be observed as changes that appear on the skin, eyes and muscles.

1) Changes in the Skin: 

Within a few minutes after death, the skin begins to lose its elasticity. In addition to this, their skin tends to become pale and ashy in appearance. The lips begin to lose moisture and slightly harden, giving it a brownish and dry appearance. 

2) Changes in the Eye:

Some of the changes in the eyes may be observed as the following:

• Opacity or Cloudiness of the Cornea
• Loss of reflex of the Pupils and Cornea: which is checked by using a torch or other light source. If the Pupils do not constrict, it indicates that it has lost its reflex. The pupils will remain dilated.
• Flaccidity of the Eyeball: The eyelids become droopy and the eyeball sinks into the eye socket.
• At a biochemical level, a steady rise in potassium level in the vitreous humour is seen, which can be detected up to 100 hours after an individual’s death. 

3) Early changes in muscle: 

After death, early change in body muscle is called the Primary Flaccidity. This is observed in the stage of somatic death and lasts for 1-2 hours after the person has died. During this phase, which occurs soon after death, all the muscles of the body begin to relax. The body flattens over the area that is in contact with the resting surface (contact flattening). The cells in the body are still alive, and anaerobic chemical processes may continue in the tissue cells. (Reddy & Murty, 2014) 

Signs of Early Post-mortem Interval (PMI)

1. Algor Mortis (Post-mortem cooling of the body):

Following the somatic death, energy and heat production within the body stops, and the body gradually starts to lose heat and finally reaches the ambient temperature.

However, the cooling does not occur at the same rate throughout the body. The body cools much faster on the exterior surface as compared to the interior of the body.

While estimating the Post-mortem Interval (PMI) based on algor mortis, the rectum is an ideal place to record temperature (Except in cases of Sodomy). This is because, unlike the other parts of the body, the temperature fall in the rectum occurs in a linear rate. Initially, ½ an hour to 1 hour after death, the rectal temperature begins to fall. This is followed by a linear rate of cooling, at the rate of 0.4- 0.6 oC, for the next 12-16 hours. (Reddy & Murty, 2014)

 However, certain factors can affect Algor mortis, such as: 

i. The difference in temperature between the body and ambient temperature: 

The rate of fall in temperature is more rapid when there is a greater temperature difference between the body and the surroundings. For example, during hot summers, the cooling of the body may slow down as a result of the temperature in the surrounding environment being much higher than the body itself.

ii. The build of the deceased: 

“Bodies in which the ratio of the surface area to body mass is large cool more quickly (eg, bodies of thin people and infants cool more quickly than bodies of obese persons).” (Postmortem Changes, 2020) (Postmortem Changes | Decomposition | Autopsy, n.d.)

iii. Covering on the body:

Clothes are bad conductors of heat. Therefore, they can hamper the rate of cooling of the body.

iv. The surrounding environment of the body:

The cooling of the body is rapid in cases where the body is found in humid conditions, windy regions, or when the body is immersed in the water. But the contrary is true when the body is found in stagnant water or sewage water (due to excessive microbial activity in the body), that slows down the cooling process. 

2) Livor mortis 

This is also known as Post-mortem Lividity, Post-mortem Staining or Post-mortem Hypostasis. In this stage, bluish-purple or purplish-red discolouration is observed on the skin. These livid stains begin to form on the parts of the body which is in contact with a resting surface. They begin to appear within 0.5-2 hours after death and are fully developed by 6-12 hours.

The discolouration occurs as a consequence of the cessation of blood circulation, which causes the blood to become stagnant and thus, the red blood cells begin to settle down due to gravity. (Jaypee Brothers (Jaypeedigital), 2010)

Importance of Livor mortis in the estimation of Post-mortem Interval (PMI):

• Dull purple-black spots of approximately 1-2 cm diameter, begin to appear in 20 to 30 minutes- 2 hours after death. These are called as “Tardieu Spots”. (Reddy & Murty, 2014)
• These spots gradually increase in size and appear more intensely coloured. In 4-5 hours, the spots appear to have merged to produce extensive discolouration. 
• By 6-12 hours after death, the spots become constant and will persist until the decomposition stage begins.
• The main medico-legal importance of livor mortis is that, if the body has been displaced or moved to a different posture within few hours of death, the patches of lividity may fade and new ones appear on the parts of the body that’s in contact with the resting surface. However, few traces of the lividity will remain in the original area. Therefore, this can help determine whether the body was moved or displaced from its original position. (Reddy & Murty, 2014)

3) Rigor mortis (Death Stiffening or Cadaveric rigidity) 

This is the post-mortem stiffening of the body muscles, as a result of the shortening of the muscle fibres. At this stage, the individual cell death begins to take place, certain biochemical changes in the muscle. The muscles begin to stiffen 4 hours after death. By the end of 8-12 hours, the stiffening extends to the entire body.

Rigor mortis affects both, voluntary and involuntary muscles of the body. The stiffening of the muscles occurs sequentially. The first to stiffen are the muscles of the eyelids. This is followed by the muscles in the neck region, lower jaw, facial muscles, chest muscles, upper limbs, abdominal muscles, and lower limbs. The fingers and toes, stiffen last.

 Why do the muscles stiffen?

Our muscles are made up of densely packed muscle fibres known as “Myofibrils” which extends throughout the length of the muscle. These myofibrils are made up of two protein filaments named, “Actin” and “Myosin”. Under the influence of a nerve signal, our muscles contract as a result of the interlocking of actin and myosin protein filaments. The muscles continue to remain contracted until there is a sufficient level of ATP in the muscle to enable the detachment of the cross-linking fibres. 

However, once the molecular death begins, the cells begin to die as a result of the lack of oxygen in the body, which stops the biochemical reactions and exchanges that are required for muscle relaxation. 

 Importance of Rigor Mortis in estimation of Post-mortem Interval (PMI):

The extent to which the rigor mortis has developed in the body can help estimate how long it has been since the person died.

It must be noted that the duration of the rigor mortis can vary depending on the climatic conditions. In India, the usual duration of rigor mortis is between 24- 48 hours in winters, and 18-36 hours in summers. The rigor mortis will continue to persist until the decomposition of the muscle fibres takes place, due to the action of microbial activity. 

Factors affecting Rigor Mortis: 

While analysing the rigor mortis on the body, one must always keep in mind the following factors: 

i. Age of the Deceased: 

• Rigor mortis is not observed in a foetus below the age of 7 months. 
• It develops early in children and aged persons.

ii. Nature of Death:

• Rigor mortis sets in early and lasts for a shorter duration in those who die due to exhaustion (For example, Fatigue, Typhoid, TB, Cholera, etc.)
• Late-onset of Rigor mortis is seen in cases of death due to Paralysis, haemorrhage, etc. 

iii. Atmospheric Conditions: 

• Faster onset and development of rigor mortis occurs in hot weather conditions.
• Slow and long duration of rigor mortis is observed in cold weather conditions.
• Dry air and cold water can prolong the duration of the rigor mortis.

Decomposition:

After one dies, even though the decomposition of the body is not apparent until much later, this process begins at the point of death and continues from then on, until the body is skeletonized. The decomposition process can be broken down into a series of stages. (Lee Goff, 2009)

However, for a much-simplified understanding, we can classify it into 2 main stages, which constitute the process of Autolysis and Putrefaction.

I. Autolysis: 

The term ‘Autolysis’, refers to the self-digestion of tissues. This stage of decomposition begins soon after death when the cell membranes become permeable and begin to breakdown. Even though the bacterial activity has not yet begun at this stage, the organs gradually start to disintegrate. 

II. Putrefaction: 

Very often, the terms decomposition and putrefaction are used interchangeably. It is said to be the final stage of death. This stage often follows the phase of Rigor Mortis. By this time, there can be visible and sometimes quite grotesque changes that can be seen on the body. These changes arise as a result of bacterial and entomological activity. 

Several factors affect the decomposition process of the body. It includes temperature, humidity, the health of the deceased, and the conditions surrounding the body, etc.(Sharma, 2014)

Due to varied climatic conditions across various parts of the world, it is not accurate to generalize the stages of decomposition. Nevertheless, the following characteristics seen during putrefaction can be used as a basic ground rule while dealing with decomposed bodies:

1. Changes in colour & Abdominal Swelling: 

As a result of the excessive bacterial activity from within the abdominal wall of the body, the first external sign of putrefaction is seen as a greenish-black discolouration of skin in the stomach and abdominal region. The superficial veins will appear distinctly from within the skin, in a greenish-brown pattern that resembles the branches a tree. This is called the “Marbling Effect” of the skin, which lasts for 36-48 hours. (Reddy & Murty, 2014)

The abdominal swelling starts within 24 hours after death and becomes prominently visible by the end of 48 hours since the death occurred. In this phase, the organs gradually become a soft disintegrating mass of flesh. In addition to this, foul-smelling gases begin to emanate from the body, because of the production of ammonia, hydrogen sulphide, methane, etc., as a result of the bacterial activity. (Reddy & Murty, 2014) The smell of these gases starts attracting insects such as Blowflies, Flesh Flies, Muscid Flies, to the dead body. They start feeding on the blood and the fatty tissues of the body and search for suitable sites to lay their eggs.

2. Bloat Stage: 

The bloating of the body cavities occur due to the excessive production of gases within the body as a result of the microbial activity. At this stage, the nails and hair can be pulled off easily. The skin present on the hands may also peel off, coming off like a glove. (Lee Goff, 2009) By the end of this stage, we may find that the eggs of the insects’ hatch and the maggots (Insect larvae) coming out of it start feeding off the body, and begin to grow in size.

3. Liquefaction of the tissues:

In this stage, the tissues are completely disintegrated to appear as a thick, semi-fluid, back mass. This takes about 5-10 days after death. By this time, the abdomen bursts open due to the excessive pressure exerted by the gases produced inside. The teeth can be easily pulled off at this stage. Around the 4th -8th day of this stage, the maggots stop feeding on the flesh and move to a damp and dark region of the body, or maybe slightly away from the body, to pupate, and by the end of 12 days, they emerge into flies. (Sharma, 2014)

4. Skeletonization: 

At this stage, the body is completely reduced to skeletal remains. The rate at which the body is skeletonized depends on environmental factors such as the climate, the amount of soil, water, air circulation, insect colonisation of the body, whether the body is buried directly or wrapped in some material or enclosed in a coffin, and also the depth of the burial matters.

The time taken for a body to completely skeletonize varies substantially. For example, the complete skeletonization if of an un-coffined body takes about a year, whereas, in a coffined body, the skeletonization process may be moderately delayed. (Reddy & Murty, 2014)

Modification of Putrefaction

1. Adipocere Formation (Saponification) 

This is different from the usual process of decomposition. This is observed in cases where the body is found in extremely moist, warm and lack of oxygen, that favour Adipocere formation. For example, such as being immersed in water or damp places. An Adipocere layer is formed on the body, due to the gradual decomposition of the fat present in the body. In these cases, the body is found to have a whitish, smeary, mouldy or putrid-smelling layer of fat. The formation of fat may begin immediately, however, sometimes it may take about two weeks to 2 months.

2. Mummification

This takes place in dry and hot climates, like the desert or in dry and confined spaces. The moisture in the body is completely evaporated by the action of the continuous hot air on the body, which entirely dehydrates the body. This may take 3 months to a year. This is characterized by the formation of a dry and brittle layer over the body, and the body might appear shrivelled. The mummification of the body often helps in the preservation of the body features. This may sometimes ease the process of identification. (Forensic Science (2008) – (Malestrom).Pdf, n.d.) 

Therefore, from all the details mentioned above, we can get a better insight on how forensic investigators deal with cases of deceased individuals, and how they estimate the approximate time of death of the individual by identifying & interpreting the various post-mortem changes that occur in the body of the deceased. 

References:

1) Forensic Science (2008)—(Malestrom).pdf. (n.d.).

2) Forensic Thanatology | List of High Impact Articles | PPts | Journals | Videos. (n.d.). Retrieved October 7, 2020, from https://www.longdom.org/scholarly/forensic-thanatology-journals-articles-ppts-list-2264.html

3) Jaypee Brothers (Jaypeedigital). (2010). Textbook of Forensic Medicine and Toxicology.

4) Lee Goff, M. (2009). Early post-mortem changes and stages of decomposition in exposed cadavers. Experimental and Applied Acarology, 49(1–2), 21–36. https://doi.org/10.1007/s10493-009-9284-9

5) Postmortem Changes | Decomposition | Autopsy. (n.d.). Scribd. Retrieved October 8, 2020, from https://www.scribd.com/document/326421172/Postmortem-Changes

6) Postmortem Changes: Overview, Definitions, Scene Findings. (2020). https://emedicine.medscape.com/article/1680032-overview

7) Reddy, N. K. S., & Murty, O. P. (2014). The essentials of forensic medicine and toxicology.

8) Sharma, B. R. (2014). Forensic Science in Criminal Investigation & Trials (5th ed.). New Delhi: University Law Publishing Co. Pvt. Ltd.

9) Wardak, K., & Cina, S. (2011). Algor Mortis: An Erroneous Measurement Following Postmortem Refrigeration. Journal of Forensic Sciences, 56, 1219–1221. https://doi.org/10.1111/j.1556-4029.2011.01811.x