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Late Post Mortem Changes

Post mortem changes are classified into three sequential stages: immediate, early, and late. The late changes encompass all processes of decomposition and decay - specifically putrefaction, adipocere formation, and mummification.

Classification of Post Mortem Changes

Stage	Key Changes
Immediate (somatic death)	Insensibility, cessation of respiration and circulation
Early (cellular death)	Pallor, eye changes, cooling, lividity, rigor mortis
Late (decomposition and decay)	Putrefaction, adipocere, mummification

The Essentials of Forensic Medicine and Toxicology, 36th ed. (2026), Table 7.1

1. PUTREFACTION

Putrefaction is the decomposition of organic material by microorganisms. It is driven by two major processes:

A. Autolysis ("Self-digestion")

When the heart stops, oxygen is depleted and CO2 levels rise, poisoning cells. pH decreases and lysosomal enzymes digest proteins, breaking down cellular structures. The bowel decomposes fastest (high natural bacterial content); skin is more likely to mummify.

Order of tissue decomposition by autolysis:

Digestive organs, blood, circulatory system
Air passages and lungs
Kidneys and bladder
Brain and nervous tissue
Skeletal muscle
Connective tissue

B. Putrefaction (bacterial)

Bacteria from the GIT and environment invade tissues, producing foul-smelling gases (H2S, CO2, methane, ammonia). These gases cause swelling and discolouration.

Order of tissue decomposition by putrefaction:

Air passages and lungs
Digestive organs, heart, and blood
Brain and nervous tissue
Kidneys and bladder
Skeletal muscle
Connective tissue

Forensic Anthropology: A Comprehensive Introduction, 2nd ed., Tables 15.1 & 15.2

External Signs of Putrefaction - Timeline

~24 hours:

Greenish discolouration appears first over the right iliac fossa (caecum) - the first sign externally - then spreads over the entire abdomen and chest

~36 hours:

Marbling - veins appear as greenish-black branching networks under the skin due to haemolysis and diffusion of altered haemoglobin through vessel walls
Putrefactive blisters (bullae/blebs) - appear under the skin at 36-48 hours. They contain gas and reddish fluid. When punctured, no vital reaction is seen. When they rupture, raw skin patches resembling scalds may appear. Do NOT confuse with burn blisters

~48-72 hours:

Enormous swelling (bloating) of the body due to gas accumulation, especially of the abdomen, face, lips, scrotum/penis
Rectum protrudes at 48-72 hours
Cervix of uterus protrudes in women; in pregnant women, foetus may be expelled (postmortem delivery - "coffin birth")
Skin splits from pressure; collar marks from clothing may simulate strangulation marks

~3-7 days:

Teeth become loose and may fall out; teeth may turn pink due to diffusion of haemoglobin into dental canaliculi
Skull sutures in children/young persons loosen; liquefied brain may run out

~5-12 days:

Colliquative putrefaction begins - tissues soften, loosen, and convert to semi-fluid black mass
Indistinct viscera

~2-3 weeks:

Viscera become unrecognizable
Cavities may burst; abdomen bursts with protrusion of stomach and intestines
In children, thorax also bursts

~1-3 months:

Soft tissues separate from bones - skeletonisation
Cartilages and ligaments soften and degrade
Orbits become empty

~1 year (tropics, uncoffined):

Bones begin to decompose
In coffins: 3-10 years

~10-25 years:

Bones may be totally destroyed
Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology

Internal Changes of Putrefaction

Stomach: Dark-red irregular patches appear first on the posterior wall, then the anterior wall. May perforate (autolytic perforation) - must be differentiated from corrosive acid perforation (which shows mucosal corrosion, ragged irregular margins) and peptic ulcer perforation (indurated, regular, punched-out margins with adhesions).

Liver: Softens early due to autolysis; gas bubbles (intrahepatic gas) develop.

Brain: Rapidly putrefies (often faster than abdominal viscera when submerged in water); liquefies and may run out through skull sutures in children.

Shifting postmortem lividity: As putrefaction progresses, blood clots liquefy and are haemolysed. Gas pressure can displace lividity in any direction - inference about body position is markedly weakened once putrefaction begins. Lividity extending to the head may simulate signs of violence to the neck.

Signs Produced by Putrefactive Gases (Medicolegal Importance)

Body bloating can simulate antemortem swelling
Purging of dark fluid from natural orifices (nose, mouth) can simulate haemorrhage
Distension of genitalia may suggest sexual assault
Collar/clothing pressure marks may simulate strangulation
Green discolouration and skin peeling simulate scalds or burns
Greenish-black lividity can simulate bruising

Maggot Activity (Forensic Entomology)

Flies are attracted 18-36 hours post mortem and lay eggs in open wounds and natural orifices (nose, mouth, vagina, anus). Eggs hatch into maggots (larvae) within ~24 hours. Larvae develop into pupae in 4-5 days, and pupae into adult flies in a further 4-5 days. Maggot analysis (forensic entomology) helps estimate time of death and can reveal the presence of drugs.

Putrefaction in Water

Bodies submerged in water putrefy more slowly than in air because of:

Exclusion of air
Protection from clothing
Lower water temperature (compared to atmospheric temperature)

However, on removal from water, putrefaction accelerates rapidly (tissues are fluid-saturated).

Rule of thumb: 1 week on the surface = 2 weeks in water = 8 weeks in a burial environment.

Order of external colour changes differs in water vs. air:

Decomposition in Water	Decomposition in Air
Face and neck, thorax, shoulders, arms	Abdomen, chest, face and neck, legs, shoulder, arms

Internally, the brain putrefies before abdominal viscera in water.

Flotation of submerged bodies occurs when sufficient gas accumulates - ~24 hours in summer, 2-3 days in winter. The abdomen floats uppermost (gas-filled intestines are lighter; spine is heavier).

Factors Modifying Putrefaction

External (Environmental) Factors:

Temperature: Putrefaction begins at ~10°C and is optimal at ~37°C. Cold retards; heat accelerates. Temperature accounts for ~80% of variability in decomposition rates
Moisture: Required for bacterial activity; dry conditions inhibit putrefaction
Air/Oxygen: Aerobic decomposition is faster than anaerobic. Burial >2 feet deep slows decomposition significantly
Burial depth and method: 1 week surface = 2 weeks water = 8 weeks buried

Internal Factors:

Age: Infants decompose faster; the elderly decompose slowly
Sex: Females (higher fat content) may float sooner; adipocere more common in females
Cause of death: Sepsis, wasting diseases (cholera, TB, cancer) accelerate putrefaction; sudden violent death, poisoning with HCN or strychnine accelerates it; asphyxia and haemorrhage may delay it

Case-specific:

Trauma/surgery creates additional entry points for arthropod colonization and accelerates decomposition
Animal scavenging (jackals, crows, rodents) can skeletonize a body within 24 hours outdoors

2. ADIPOCERE FORMATION

Definition: Adipocere (Latin: adeps = fat, cera = wax) is the conversion of body fat into a firm, greyish-white, soap-like substance through saponification - the hydrolysis of neutral fats (triglycerides) into fatty acids that combine with calcium and sodium to form soaps/lipids.

Conditions Favoring Adipocere

Warm, moist, alkaline environments
High humidity or burial/submersion
Warm water submersion
More common in obese individuals, females, and infants (higher adipose tissue)

Two Forms

Form	Mechanism	Texture
Hard, crumbly variety	Sodium reacts rapidly with interstitial fluid	Firm
Soft, paste-like variety	Potassium reacts slowly with adipose cell membranes	Soft, waxy

Timeline

Can begin within weeks in warm, moist environments
Full adipocere formation may take months to years

Medicolegal Importance

Preserves the shape of the body - enables identification
Helps estimate time since death
Injuries to the body may be preserved within the adipocere, aiding in determining cause of death
Unique volatile fatty acid (VFA) composition specific to human adipocere

Forensic Anthropology: A Comprehensive Introduction, 2nd ed.

3. MUMMIFICATION

Definition: Mummification is the desiccation (drying out) of the body tissues, preserving the body in a shrunken, dried state.

Conditions Favoring Mummification

High heat, low humidity, and adequate airflow (the opposite of adipocere conditions)
Hanging position (air circulates around entire body)
Arid, hot environments (deserts)
Can also occur in cold, dry climates (cold and dry during cooler months in temperate regions)

Process

Begins with drying of the face, hands, and feet
Produces brown to golden-brown discolouration and shriveling/wrinkling of skin
Connective tissues (ligaments, tendons) and overlying skin dry out first
Internal organs may undergo rapid putrefaction while superficial tissues mummify

Medicolegal Importance

Body is preserved - identification possible
Injuries may remain recognizable
Cause of death may be determinable
Time since death can be estimated

MCQ note: Mummification occurs in a dry and hot (or dry and cold) climate; adipocere occurs in warm, moist, alkaline conditions.

Summary Comparison

Feature	Putrefaction	Adipocere	Mummification
Process	Bacterial/autolytic decomposition	Saponification of fat	Desiccation
Environment	Warm, moist, air exposure	Warm, moist, anaerobic/submerged	Hot, dry, good air flow
End result	Skeletonization	Waxy, soap-like mass	Shrunken, dried, preserved body
Time since death	Can be estimated in early stages	Weeks to months	Weeks to months
Medicolegal value	Can obscure injuries; gas artefacts	Preserves body form; injuries retained	Preserves body form; injuries retained

Sources:

The Essentials of Forensic Medicine and Toxicology, 36th edition (2026), Chapter 7
Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology, Chapter 11
Forensic Anthropology: A Comprehensive Introduction, 2nd ed., Chapter 15

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