Q1. Discuss (give an account on) postmortem lividity (Hypostasis)? Explain its characteristic features and the forensic significance? (5 points)
Q2. What are the postmortem changes that may replace putrefaction? Explain the forensic significance of each one of these changes? (5 points)
Cause of Death: In certain poisonings (e.g., carbon monoxide), the color of the lividity is characteristic and can suggest the cause of death.
Differentiating Lividity from Bruises: Unlike a bruise (contusion), lividity is not swollen, and the color is confined to the skin layers. A bruise shows tissue injury and extravasation of blood into soft tissues.
Putrefaction is the main process of decomposition involving the breakdown of soft tissues by bacterial and fungal action. Under specific environmental conditions, alternative decomposition pathways may occur, essentially replacing or significantly modifying the typical putrefactive process. These are known as late postmortem preservative changes.
The two main changes are Adipocere Formation and Mummification.
| Feature | Description |
| Definition | A chemical process where body fats are converted into a waxy, greasy, grayish-white to tan substance composed primarily of fatty acids (like palmitic, oleic, and stearic acid). |
| Conditions | Requires a moist, anoxic (oxygen-deprived) environment (e.g., bodies submerged in water, damp earth, or buried in clay soil) and moderate temperatures. |
| Timeline | Usually begins after about 3 weeks, becoming fully developed in 3–6 months. |
| Forensic Significance | ∙ Identification: The process preserves the facial features, body shape, and identifying characteristics (like scars, tattoos) for extended periods, aiding in visual identification even months or years later. ∙ Time Since Death (PMI): Provides a broad estimate of the minimum time since death, indicating a duration of weeks to months. ∙ Manner of Death: Can sometimes protect evidence of trauma or wounds that would have been destroyed by putrefaction. |
| Feature | Description |
| Definition | The widespread drying and shrinking of the body tissues, resulting in a tough, leathery, dark-brown, and relatively odorless preservation of the body. |
| Conditions | Requires a dry environment with moving air (e.g., desert, attic, bodies exposed to high winds) and can be hastened by high heat. It is essentially extreme dehydration that inhibits bacterial growth. |
| Timeline | The time required is variable, from a few weeks to several months, depending on the size of the body and the ambient conditions. |
| Forensic Significance | ∙ Identification: Like adipocere, the preservation of features, particularly the skin, hair, and clothing, significantly aids in the identification of the deceased. ∙ Time Since Death (PMI): Provides a rough estimate of the minimum time since death (weeks to months or longer). ∙ Trace Evidence: Because the body is dried and intact, it is excellent for the preservation of trace evidence (e.g., hair, fibers, insects, foreign DNA) which can be easily lost in a putrefied body. ∙ Cause of Death: Injuries like stab wounds or bullet holes may be remarkably well-preserved. |
Postmortem lividity (Livor Mortis or Postmortem Hypostasis) is an early postmortem change characterized by a discoloration of the skin due to the passive process of blood settling in the capillaries and small vessels of the dependent (lowest) parts of the body due to gravity, following the cessation of circulation. It is Latin for "bluish color of death."