An elderly woman, who was a matron at a boarding school, was found dead in her bed one morning. It had been very cold the previous night, and the woman lit a charcoal stove to add some warmth to the room. Unfortunately, the room had a very poor ventilation system.
Two other women also died under similar circumstances. The two were working in a popular food vending joint. The day they died, they had got to the workplace quite early in the morning and set about preparing the day’s food. They cooked in a poorly ventilated room. Unfortunately, it was very cold and rainy that morning, and the women closed the only door of the kitchen. An hour or so later, they were found dead in the room.
All three bodies were taken for post-mortem, and the most striking feature on the bodies was the reddish (cherry red) discolouration of the organs. The cause of death of these three women, as established at post-mortem, was due to carbon monoxide poisoning, which in all the cases was accidental.
Carbon monoxide is a deadly gas produced when carbon burns in limited amounts of oxygen, especially in environments of poor ventilation. Most fuels such as charcoal, kerosene or petrol contain high amounts of carbon. In adequate amounts of oxygen, carbon will burn and produce carbon dioxide and water, but in limited oxygen, carbon monoxide is produced instead of carbon dioxide.
Carbon monoxide poisoning is very common and much more common than is suspected. One of the reasons is that the gas is colourless, is non-irritating and has no smell. The toxic effects of the gas are also insidious, and this makes it all the more difficult to detect. Most of the deaths attributed to carbon monoxide poisoning are accidental, but some have, however, been suicidal. Deliberate poisoning by carbon monoxide is, however, rare. Nevertheless, it was used in the Nazi gas chambers.
Once death has occurred, the heart stops pumping blood to parts of the body, and the blood that is in the body gravitates to the dependent parts of the body. This is seen as the dark purple discolouration of the skin and is more pronounced in light-skinned individuals. Blood in the dead, is dark-coloured, as the blood no longer contains oxygen, which is responsible for its bright red colour. In anaemic persons or people who have had severe blood loss before death, there is a very significant delay in the development of this discolouration, also known as post-mortem staining.
Initially, some blood clots are formed in the body as soon as death occurs. However, blood in the dead cannot clot 30 to 60 minutes after death as substances which breakdown blood clots are released once death has occurred. Therefore, blood remains in the liquid state in the blood vessels after death rather than clotting. The blood clots seen in a dead body are, in truth, those which are too big to be broken down by these substances.
The particular nature and the distribution of the discolouration are of great importance in death investigations. In deaths from carbon monoxide poisoning, the skin and internal organs of the body will appear cherry red in colour. Cyanide poisoning causes the body and its organs to have a violet colour or bright red. In deaths due to exposure to cold, the body may have a bright pink appearance.
Discolouration of a body is first apparent about 20 to 30 minutes after death, and these begin as dark red patches which deepen in intensity and merge into one another progressively to form the extensive areas of reddish-purple discolouration. In about 10 to 12 hours, the discolouration in a particular place becomes fully established to the extent that if the position of a dead body is changed, the discolouration will remain in that place in which it was initially established. Well-developed discolouration fades very slowly and incompletely. However, the development of post-mortem staining is not a useful indicator of the time of death.
When a dead body is moved after the discolouration has been established, another discolouration will also occur in accordance with the new position of the body, and this is known as a secondary pattern of discolouration. This secondary pattern will even develop when a body is moved after 24 hours. When a dead body has these two patterns of discolouration, the primary and the secondary, it implies that the body must have been moved after death occurred. Fading of the primary discolouration will be quicker and more complete if the body is moved within the first six hours after death.
Application of pressure prevents blood from filling the blood vessels in the toneless areas, and such areas will be devoid of discolouration and will appear pale. This is commonly seen in the buttocks and back of a dead body facing upwards. These pale areas are also seen in areas affected by tight clothing, belts, or any firm object lying beneath the body, including the arm of the deceased. The distribution of discolouration and pale areas on a dead body will, therefore, depend on the position of the body at the time of death. An unexplained pale area on a dead body without any firm supporting object will also mean that the body must have been moved after death.
In a case in which an inmate was alleged to have hanged himself in a holding cell in a police outpost, it was found that there was an unexplained pale area in one of the upper arms of the inmate. This led to the inevitable conclusion that the body of the inmate must have been lying on its side before the body was hanged up to simulate suicide.
The discolouration due to gravitational pulling of blood also occurs in the internal organs and may be mistaken for pneumonia when it occurs in the lungs or a heart attack when it involves the heart.