When a person dies, they leave a body. How does the body change after death? There are four main post-mortem events: algor mortis, livor mortis, rigor mortis and putrefaction. Forensic pathologists use these phenomena and an autopsy to determine the time of death, hearing out the final words of the deceased.
With death, all physiological functions cease. Therefore, the body produces no more heat and begins to cool (algor mortis), evident when touching the corpse. The rectal temperature is measured for an accurate reading.
As blood is no longer flowing, red blood cells sink due to gravity. They sink to capillaries in the lowest point of the body, causing a purple-red rash on the skin of the area. This is known as livor mortis, or lividity. It appears first about 1~2 hours after death, and worsens with time. On the other hand, the other areas of skin become pale due to the lack of blood.
2~3 hours post-mortem, one can observe the jaw stiffening. This is called rigor mortis. It is caused as ATP is needed for muscle relaxation, and ATP production stops with death. This leads to the muscle becoming rigid, fixating on the position at the time of death. About 6~7 hours later, rigor mortis spreads to the entire body and completely fixes the body 10~12 hours later. After about 72 hours, rigor mortis dissipates and the corpse is limp again.
Putrefaction is the process of microbes decomposing the body – more commonly called rotting. After death, cells die from the lack of energy and are broken down by enzymes. As the immune system also ceases function, microbes easily infiltrate the body and begin converting organic material into inorganic material.
Microbes release gases as it digests the corpse, which collects and causes bloating. The main gases are carbon dioxide, methane and hydrogen sulphide, producing the rotting smell, attracting insects to the corpse.
The key insects studied by pathologists are arthropods and flies. They can estimate the time of death from observing what species are present on the body, and at what stage of the life cycle they are at. For example, 0.5~1 hour post-mortem, flies arrive and lay eggs, which hatch into maggots at 10~24 hours, which becomes cocoons after 8~12 days, which hatch into adult flies at 12~14 days post-mortem.
There is no dignity in death. The rich, the powerful, the kind, the happy – everyone rots away by nature after they die.