Thanatology, (from Greek thanatos, “death”) the description or study of death and is concerned with the notion of death as the branch of science that deals with death in all its aspects.
The following changes are seen after death is classified as:
- Immediate Changes (Somatic death)
- Early Changes (Cellular death)
- Skin changesThe blood circulation to the skin is stopped resulting in pallor and loss of elasticity.
- Eye changesAn early change in eye seen as opacity of cornea and flaccidity of eyeball due to loss of intraocular tension, which progressively comes down to zero in about 2 hours.
- Algor mortis (Postmortem cooling)Is a progressive loss of heat due to; conduction, convection and radiation after death resulting in cooling of body.
- Livor mortis (Postmortem lividity)A passive pooling imparts reddish-purple or bluish discoloration of skin in dependent parts of the dead body is called as livor mortis with “contact flattening” on pressure areas of the body.
- Rigor mortis (Postmortem rigidity)A state of stiffening of muscles after death due to physiochemical process due to ATP is progressively and irreversibly destroyed by dephosphorylating and deamination leading to accumulation of lactates and phosphates in the muscles.
Conditions simulating Rigor Mortis
Heat stiffening: Temperature > 65°C
Cold stiffening: Temperature < 3.5°C
Gas stiffening: After putrefaction sets in.
Cadaveric Spasm/Instantaneous Rigor
In cases of sudden death from excitement, fear, severe pain, exhaustion etc. muscles that were contracted during life become stiff and rigid immediately after death without passing through stage of primary flaccidity due to which exact attitude of person at the time of death is preserved usually limited to single group of muscles frequently involving hands as seen here. This condition is known as Cadaveric Spasm or Instantaneous Rigor or Cataleptic Rigidity of the body.
- Late Changes (Decomposition)
- Putrefaction: Early sign of decomposition is greenish discoloration on right iliac fossa due to hemolysis of red blood cells and the liberated hemoglobin is converted into sulfmethemoglobin by hydrogen sulfide gas may be seen around 12–18 hours after death.
- Saponification (Adipocere)
Modified form of Putrefaction- Mummification
Skeletonization is the removal of tissues from the bones or skeleton, it may be complete; where all soft tissues are removed and partial, where only a few portions of the bones are exposed.
Artefacts
It may be regarded as any change caused or feature introduced in the natural state of the body that is likely to be misinterpreted at autopsy. These injuries may be produced by aquatic bites, ants and scavengers, etc.
Postmortem artefacts are due to any changes caused or features introduced in a body after death.
It is duty of medicolegal expert to differentiate artefacts from that of injuries thereby preventing false interpretation of finding and misleading of investigation.
Types of Artefacts
- Resuscitation artefacts
- Agonal artefacts
- Postmortem artefacts due to:
- Improper handling of the body
- Postmortem changes
- Refrigeration in cold chamber
- Decomposition
- Animal and insect bites
- Autopsy surgeon induced
- Embalming
- Exhumation.
Forensic Entomology (Entomology of Cadaver)
Entomology: Study of insects.
Forensic entomology: Use of insect knowledge in the investigation of crime, used in estimation of time since death or postmortem interval (PMI).
Principle: As the insects arrive on the body soon after death, estimating age of insects can help in estimation of postmortem interval (PMI).
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Stages of life cycle
Egg→Larvae→Pupa→Adult
Figure 8: Cadaveric spasm in the upper limbs; driver holding the steering wheel at the time of death
Marbling of skin in various parts of the body, due to invasion of microorganisms and formation of sulfmethemoglobin and thereby staining the blood vessels and then being prominent giving a marbled appearance to the skin may be seen around 24–36 hours after death (Figs 14 to 19).
Autolysis of cells due to hydrolytic enzymes after death is observed as collection of fluids in between dermis and epidermis called postmortem blisters. Loosening of epidermis from the underlying dermis is called skin slippage (Figs 20 to 26).
The putrefactive changes are seen with the advancement of postmortem interval such as; color changes, bloating of face, protrusion of eye and tongue, distention of abdomen, and postmortem purging. In males, scrotal swelling may be observed. During late decomposition process, foul smelling gases are liberated which are collected in the intestine in around 12–18 hours after death (Figs 27 to 37).
Figure 37: Protrusion of intestines on opening the abdominal cavity (autopsy conducted at the crime scene)