Note the bulging eyes, lips and face with protrusion of the tongue on this decomposing individual, all related to the decomposition process. No further info about this case.
Decomposition, or putrefaction, is a combination of two processes: autolysis and bacterial action. Autolysis is the breakdown of cells and organs through an aseptic chemical process caused by intracellular enzymes. Because it is a chemical process, it is accelerated by heat, slowed by cold, and stopped by freezing. Bacterial action results in the conversion of soft tissues in the body to liquids and gases. The chemicals produced as a result of putrefaction are cadaverine and putrescine, hydrogen sulfide and other sulfides, which generate a horrible smell.
Putrefaction begins immediately upon death and usually becomes noticeable within 24 hours. As soon as death occurs, the bacteria or microorganisms within the intestinal tract escape from the bowel into the other tissues of the body. As they grow, they begin to produce gases and other properties that distort and discolor the tissues of the body. The discoloration is a dark greenish combination of colors and is generally pronounced within 36 hours. As a result, the body begins to swell from the putrefactive gases, emitting an extremely repugnant odor.
The rate of decomposition depends on the temperature, ground conditions, amount of clothing, size of the body, etc. For example, a body in a warm climate will not only encourage insect attack from the outside, but will also increase the interior bacteria development and subsequent tissue attack from within. As the tissues inside are destroyed and enzymes released, the gases formed emit a foul and sickening smell.