Late Post Mortem Changes (Decomposition & Decay)

1. Putrefaction
2. Adipocere (Saponification)
3. Mummification
4. Maceration (in special cases)
5. Skeletonization

1. PUTREFACTION

• Autolysis - self-digestion by endogenous enzymes (no bacterial involvement)
• Putrefaction - bacterial decomposition

Autolysis

• Soon after death, cell membranes break down, releasing lysosomal hydrolases
• Earliest in: parenchymatous/glandular tissues, brain, intestinal lining, adrenal medulla, pancreas (autolyze within hours)
• Accelerated by heat; stopped by freezing

Putrefaction: Mechanism

1. Gram-negative organisms from the alimentary canal spread through tissues within 24-30 hours
2. Fall in O2 + rise in H+ concentration favors bacterial growth
3. Bacteria spread via blood vessels using protein and carbohydrates as culture media
4. Chief destructive agent: Clostridium welchii (perfringens) - causes hemolysis, liquefaction of clots, tissue disintegration, gas formation
5. Lecithinase produced by Cl. welchii hydrolyses lecithin in all cell membranes - responsible for postmortem hemolysis
6. Other organisms: Streptococci, Staphylococci, bacteroids, anaerobic lactobacilli, B. proteus, B. coli, etc.

Three Cardinal Features of Putrefaction

Color Changes (External)

• First external sign: Greenish discoloration over right iliac fossa (caecum region) - 12-18 hours in summer, 1-2 days in winter
• Hemoglobin diffuses through vessels → reddish-brown staining → greenish-black (sulphamethemoglobin)
• Marbling/putrefactive network: Green-black discoloration along superficial veins giving a tree-branch pattern (18-36 hours in summer)
• Color progresses: greenish → greenish-blue → greenish-black → black

Gas Formation

• Gases: H2S, CO2, CO, NH3, phosphorated hydrogen, methane, mercaptans
• Early stages: non-inflammable; later: H2S sufficient to burn with a blue flame
• Abdomen becomes tense/distended in 12-18 hours (summer), 1-2 days (winter)
• Eyes: become soft, cornea flattens/turns white; eyes later collapse
• Blisters: Formed in 18-24 hours first on lower trunk and thighs
• Bloating/distortion of features: 18-36 hours after death
• Pressure effects: Diaphragm forced upward → blood-stained froth from nose/mouth (looks like drowning or strangulation - medicolegally important)

Liquefaction

• Tissues progressively dissolve into soft disintegrating mass
• Epidermis loosens and peels off; nails/hair become loose

Putrefaction in Water - Casper's Dictum

"A body decomposes twice as rapidly in air as in water, and eight times as rapidly as in earth."

• More rapid in warm, fresh, stagnant, sewage-contaminated water
• Hands/feet: skin becomes bleached, swollen, wrinkled, removable as a glove (2-4 days)

Order of Organ Putrefaction

1. Larynx and trachea (12-24 hours summer)
2. Stomach, intestines, pancreas, spleen (24-36 hours summer)
3. Liver (softened in 12-24 hours; foamy/"honeycombed" by gas), Lungs
4. Brain
5. Heart
6. Kidneys, bladder
7. Prostate, uterus (highly resistant)
8. Skin, muscle, tendon
9. Bones (last to decompose)

Factors Affecting Rate of Putrefaction

• Age: Children putrefy rapidly; old people slowly; unfed newborns very slowly (sterile gut)
• Sex: No effect
• Body build: Fat/flabby bodies faster than lean bodies
• Cause of death: Rapid in septicemia, peritonitis, asphyxia, Cl. welchii infections (gas gangrene, intestinal obstruction). Delayed in anemia, wasting disease, carbolic acid/zinc chloride/strychnine/heavy metal poisoning
• Mutilation/wounds: Rapid due to easier bacterial entry

Medicolegal Importance of Putrefaction

• Time since death can be estimated (unreliable in advanced decomposition)
• Gas pressure mimics signs of drowning, strangulation, traumatic asphyxia
• Artifacts can mimic antemortem injuries
• Obscures cause of death; toxicology becomes difficult

2. ADIPOCERE (Saponification)

Mechanism

• Gradual hydrolysis and hydrogenation of preexisting fats (olein, etc.)
• Converted into higher fatty acids (palmitic, oleic, stearic, hydroxystearic acid)
• These combine with calcium and ammonium ions to form insoluble soaps
• Being acidic, these soaps inhibit putrefactive bacteria (self-preserving)
• Enzymes involved: intrinsic lipases initially, then lecithinase from Clostridium perfringens
• Fatty acids in body fat at death: ~0.5% → rise to 20% within 1 month, >70% in 3 months

Properties

• Smell: Offensive/sweetish (early: penetrating ammoniacal odor)
• Fresh: Soft, moist, whitish, translucent
• Old: Dry, hard, cracked, yellowish, brittle, inflammable (burns with faint yellow flame)
• Floats in water; dissolves in alcohol and ether

Distribution

• Forms wherever fatty tissue is present
• First in subcutaneous tissue: face, buttocks, breasts, abdomen
• Sometimes entire body converted into adipocere

Time for Formation

• Shortest: ~3 weeks (summer, temperate countries)
• Full conversion: months for hardening/swelling; rarely the whole body
• May persist for decades

Medicolegal Importance

1. Helps establish identity (face preserved)
2. Injuries recognizable - cause of death determinable
3. Can estimate time since death (not very reliable)

3. MUMMIFICATION

Features

• Begins in exposed parts: face, hands, feet → spreads to entire body
• Skin: shrunken, dry, brittle, leathery, rusty-brown to black, stretched over bony prominences
• Body loses 60-70% of weight, becomes thin, stiff, brittle
• Arms often abducted at shoulder, flexed at elbow, hands clenched (due to shrinkage of muscles and tendons)
• Internal organs: shrunken, hard, dark-brown/black, coalesce into a single mass
• Can be partial (only limb/head/trunk) or complete
• Often covered with fungal growths

Conditions Favoring Mummification

• Hot, dry, well-ventilated climate
• Desert environments (classical)
• Can occur indoors in well-heated rooms

Time Required

• 3 months to 1 year (varies with body size, atmospheric conditions)

Medicolegal Importance

• Identity preserved - facial features recognizable
• Injuries preserved - cause of death can be determined
• Time since death estimable (unreliable)

4. MACERATION

• Softening and disintegration of tissues without putrefaction (no bacterial involvement)
• Occurs in dead fetus retained in utero (sterile environment) due to autolytic fermentation
• Also occurs in bodies submerged in water - flesh strips off after several weeks under current action

5. SKELETONIZATION

• The end-point of decomposition
• Hot, humid climate + heavy insect activity: Possible in a few days
• Exposed body (flies, maggots, animals): Skeleton within a few days
• Buried in shallow grave: Moderately delayed
• Deeply buried body: Markedly delayed (low temperature, no air, no animal life)
• Bones themselves: Eventually crumble; flat bones and infant/old bones breakdown fastest
• Acidic soil destroys bones in 25-100 years; hot climate surface bones decay in 5-10 years

Summary Table: Late Post Mortem Changes