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Decomposition and its effects

Dr Stephen Cordner, various stages of decomposition, time since death, livor mortis, rigor mortis.
Understanding a bit about decomposition is important for a few reasons. First of all, it introduces artefacts which can be misinterpreted as injury. It’s an indication of time since death, but I’ll say it now, a very poor indication of the time since death. And its presence can obscure pre-existing injury. Decomposition can be regarded as the enemy of forensic pathology. But short of immediate refrigeration of the body, it’s as inevitable as night follows day. The main post-mortem changes which merged then into the decomposition process are first of all, cooling of the body. Then the development of post-mortem lividity or post-mortem staining. The development of post-mortem rigidity or stiffness.
The development of putrefaction bloating, swelling, discoloration, purging of body fluids from orifices infestation with maggots, tissue loss. And finally arriving at skeletonization.
Along the way, there can be carnivorous involvement of local fauna, rodents, cats, dogs, even domestic ones. Altering and speeding up the process of dissolution of the body.
There are also special forms of decomposition adipocere formation and mummification. Now, most of the processes mentioned above except lividity are essentially chemically mediated processes and thus temperature dependent. Lividity is essentially a physical phenomenon of blood. The circulation having stopped, blood settles under the influence of gravity and the dependent parts of the dead body. So if the body is lying on its back, the skin of the back parts of the body becomes darker than the skin on the front part of the body. Blood has moved under gravity from the front to the back. In relation to the temperature and chemically mediated post-mortem processes, rigidity comes on more quickly in warmer places. If you’ve exercised shortly before death, rigidity may appear earlier.
In hotter climates, putrefaction develops and advances quite rapidly. A body left in the sun on a hot day can swell and turn green in an hours. If nothing is done and if nothing is done to remove the body, hopefully after rapidly doing what can be done at the scene, specifically some good quality photography, then the contribution to the death investigation from the forensic pathology might be effectively lost. But in cold climate, where the atmospherics like refrigerators, the body will remain well preserved for days on end. But other factors influence things, too.
In a cold climate, for example, being really rugged up and really well insulated from the cold, might preserve enough heat for putrefaction to start, especially if you had a bit of a high temperature from an infection, for example to start with. Open injuries even in a cool climate will attract flies and thus hasten the onset of maggot infestation and tissue loss. Maggots generate heat, and when they’re in sufficient numbers, this can further accelerate things. As the body swells, pressure builds inside the body and forces fluid from the lungs and perhaps the stomach out of the mouth. This is called purge or purging. This creates an alarming appearance of possible injury.
The body discolors green, purple and black a nd the outer layer of skin begins to form blebs and blisters and easily peels off. This discoloration also easily misinterpreted by inexperienced people as injury. We could go on and on. But the important point for lawyers interested in forensic pathology and the investigation of death is first, that these changes are so variable and a conclusion of the time of death or more exactly how much time has passed since death based on an assessment of body temperature, lividity, rigidity, signs of decomposition, etc.
by forensic pathologist is so unreliable that it would be an unusual case, in my experience, where the pathologists judgment would be more valuable than the circumstantial evidence about when death occurred. And when the pathologist’s opinion is to be relied on, he or she should be asked two things. Where is the published evidence that forensic pathologists can reliably assess time since death using these or other criteria? And secondly, should be asked whether the reliability of that individual pathologist in making the assessment has ever been independently tested and reported on. If so, could we please see the results of that assessment?
And the second thing, which is important for lawyers to understand about decomposition, is that there are many things which can happen to a body during or after death, which can create artefacts, not only decomposition, things which look like disease or injury, but which are actually something else completely.

In this lesson, Dr Cordner explores the various stages of decomposition and the concept of time since death. As you watch the video, reflect on the limitations of determining time since death and correlate it with the manner in which it is described in post mortem reports. Based on these reflections, share your thoughts in the comments section below.

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Decoding Forensics for Legal Professionals

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