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Thanatology

Medico-legal study of death

Stages of Dying

1. Pre-agonal Stage
1. Loss of Consciousness
2. Falling of Arterial Pressure
3. Decrease of Level of Metabolism
2. Terminal Pause
1. Functions of Nervous System starts to have Chaotic characters
2. Arterial pressure and breath are reduced
3. Agony Stage
1. Further fall of Arterial pressure & reduction of breath, but at certain moment everything looks like they are back to normal
2. But then, all the parameters become again sharply reduced
4. Clinical Death
1. Complete oppression of consciousness reflexes, heart activity and breath.
5. Biological Death
1. It is the last stage of irreversible changes in organisms.

Classification of Circumstances of Death

1. Violent Death (Occurs due to action of environmental factors.)
1. Suicidal
2. Homicidal
3. Accidental
4. Unexplained Origin
2. Non-Violent Death (Caused only by internal reasons that are diseases)
1. Sudden Death
2. Death from Diseases
3. Physiological Death

Post-Mortem Signs

1. Immediate Signs (Somatic or Clinical Death)
1. Loss of Voluntary power
2. Cessation of Respiration
3. Cessation of Circulation
2. Early Signs (Cellular or Molecular Death) (appears 12 - 24 hours after death)
1. Changes in Skin Eyes
2. Changes in Eye
3. Livores Mortis
4. Muscular changes
5. Cooling of Body
6. Autolysis of inner organs
3. Late Signs ( appears after 24 hours of death)
1. Decomposition & Decay
1. Putrefication
2. Skelitanization
2. Preserving
1. Adipocerous formation
2. Mummification
3. Peat hardening
4. Miscellaneous

Early Post-Mortem Signs

Changes in Skin

1. Skin becomes pale and ashy-white and loses elasticity within few minutes of death
2. Lips tends to darken due to drying
3. Skin becomes dry due to evaporation of moisture & its a physiological process

Changes in Eye

1. Opacity of Cornea
1. Opacity is due to drying
2. If eyes are closed, the opacity is delayed and cornea remains clear for 2 hours
3. Larcher’s Spots appear on sclera within 3 hours if eyes are opened
2. Pupils
1. Dilated because of relaxation of muscles of Iris
3. Retinal Vessels
1. Segmentation of blood columns in the retinal vessels appear within minutes after death.
4. Chemical Changes
1. A steady raise in potassium values occurs in Vitreous Humor after death.

Livores Mortis

1. This is bluish-purple or Purplish-red discoloration, which appears under the skin in most superficial layers of Dermis
2. It is caused by stoppage of circulation, stagnation of blood in vessels and its tendency to sink by force of gravity.
3. The intensity of color depends upon the amount of reduced hemoglobin in blood.
4. The blood tends to accumulate in subcutaneous tissue of dependent parts of body.
5. Filling of these vessels produce a bluish-purple color to adjacent skin.

Stages of Livores Mortis

• Hypostasis
• Outflow of blood through vessels downwards
• It begins as patchy mottling of skin
• It is well developed within 4 hours and reaches maximum between 6–12 hours.
• The area then enlarge and unite to produce extensive discoloration.
• Stasis
• If the body is moved before the blood coagulated, the Hypostasis patches will disappear and new ones will form
• But Livores Mortis to a slight degree remains in Original area.
• Imbibition
• As the vessels walls becomes permeable due to decomposition, blood leaks through them and stains the tissue.
• At this stage, Hypostatis does not disappear, if a dynamo-meter or finger is firmly pressed against the skin.

Medico-Legal importance of Livores Mortis

• It is an absolute sign of death
• It helps in estimating time of death
• Sometimes the color may indicate the cause of death
• It indicates posture of body at the time of death
• It may indicate moving of body to another position sometimes after death

Muscular Changes

3 Stages :

1. Primary Relaxation (Primary Flaccidity)
1. At this stage, death is somatic and lasts for 1–2 hours
2. All muscles begin to relax soon after death
3. Muscular response to mechanical or electrical stimuli persists.
2. Rigor Mortis (Begins 1–2 hours after death and continue till 24–48 hours)
1. This is a state of stiffening of muscles, sometimes with a slight shortening of fibers.
2. Individual cell death takes place
3. When Rigor is fully developed, the entire body is stiff, muscles are shortened, hard and opaque
4. Knees, hips, shoulders and elbow are slightly flexed and fingers & toes show high degree of flexion
5. After cardiac arrest, the heart is in diastolic state.
6. If Uterus is in labour at the time of death, Rigor Mortis may cause the uterus to contract and expel the fetus
3. Secondary Relaxation (Secondary Flaccidity )
1. In conditions of loss of viability of muscular tissue, gradually occurs autolysis of Actomyosin, which becomes soluble.
2. Major proteolytic enzymes are Cathepsins & Calpains.
3. These enzymes act as myofibrilar proteins and hydrolyze them
4. Develops at the end of 3–4 days

Medico-legal importance of Rigor Mortis

• It is absolute sign of death
• It helps in estimating the time of death
• It indicates posture of body at time of death

Cooling of Body

• Body cools more rapidly on surface and more slowly in interior.
• Body heats is lost by evaporation, convection and radiation.

Factors affecting the rate of cooling

1. Difference in temperature between body and medium
1. The temperature falls rapidly when the difference between body and air is great.
2. In tropical climate: 0.5–0.7 Degree Celsius/hour
3. In temperate countries : 1 degree Celsius/hour
2. The build of Cadaver
1. The rate of heat loss is proportional to the weight of body to its surface area.
2. Thus children & old people cool more rapidly than adults.
3. Physique of Body
1. Fat is bad conductor of heat
2. Fat bodies cool slowly and lean bodies cools rapidly
4. Covering around the body
1. Clothes are bad conductor of heat
2. Rate of cooling is slow when the body is clothed

Medico-legal importance of cooling of body

• It is absolute sign of death
• It helps in estimating the time of death
• It helps in estimating reason of death

Autolysis

1. Autolysis is self-digestion of tissues, caused by actions of proteolytic enzymes.
2. Proteolytic enzymes are Pepsin and Tripsin
3. Autolysis is shown in organs with high proteolytic enzymes such as pancreas, adrenal glands, stomach, spleen and liver

Late Post-Mortem Signs

Putrefaction

1. It is the final stage following death, produced mainly by action of bacterial enzymes.
2. These are anaerobic organisms derived from bowel.
3. Chief bacterial agent is C. Welchii which produces Lecithinase.
4. This hydrolyzes the lecithin present in all cell membranes and is responsible for haemolysis of blood.
5. Other agents are Streptococci, staphylococci, etc…

Features of Putrefaction

1. Changes in Color of Tissue
1. First external sign of putrefaction in body is greenish discoloration of skin
2. The color appears in 12–18 hours in summer & 1–2 days in winter
3. The green coloration then spreads over entire abdomen, external genitals and these patches becomes dark green & later dark blue.
4. The earliest internal change is a reddish-brown discoloration of inner surface of vessels, especially of aorta.
2. Collecting of gases in tissue
1. Chemical process in this stage is proteins and carbohydrates being split into simpler compounds.
2. Gases are inflammable at early stages.
3. But as decomposition progress, enough of Hydrogen Sulfide is formed, which can be ignited to burn with blue flame.
4. Gases collect in intestines in 12–18 hours.
5. Gas bubbles accumulate the tissues causing crepitation and soon begin to distenol the body.
6. From 18–36 hours after death, gases collects in tissues, cavities and hallow vasera.
3. Liquefaction of tissues
1. Collective putrefaction begins from 5–10 days after death.
2. Abdomen bursts and stomach & intestines protrude.
3. In children, thorax also bursts.
4. Cartilages & Ligaments are softened in final stage.

Skeletanization

1. In case of exposed body, flies, ants, rats, dogs etc… may reduce the body to skeleton within few days.
2. When body is in water, it can be attacked by fishes & Crabs, which reduces to skeleton within few days.
3. In deeply buried body, lower temperature, no air and absence of animal life delay the process of decomposition.
4. Acidic soil may cause delay in about 25–100 years.
5. Neutral soil may not cause decay at all.

Adipocere Formation (Saponification)

1. In this, the fatty tissues of body changes into a substance known as Adipocere.
2. This change is due to hydrolysis of pre-existing fats into higher fatty acids.
3. These higher fatty acids being acidic, inhibits putrefaction bacteria.
4. Fresh Adipocere is soft, moist, whitish and translucent.
5. Old samples are dry, hard, yellowish & brittle.

Medico-legal importance of Adipocere formation

• Cause of death can be determined.
• Time since death can be determined.
• It indicates place(such as water or moist ground) from where the body has been removed.

Mummification

1. Drying of cadaver occur from evaporation of water but natural appearance of body are preserved.
2. It begins in exposed body parts and later extends to internal organs.
3. The skin is dry, brittle and rusty-brown in color.
4. Two factors are necessary for the mummification
1. Absence of moisture in air.
2. Continuous action of dry or warmed air.

Medico-legal importance of Mummification

• It indicates place from which body has been removed