Time Since Death. CHS Forensics. Crime scene. The body must first be checked for signs of life. The body must not be moved. Photographs need to be taken to record the scene. Crime scene.
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The body must first be checked for signs of life.
The body must not be moved.
Photographs need to be taken to record the scene.
Establishing the time of death is of assistance in any police investigation of a death, whether it was from natural or un-natural causes.
Establishing the time of an assault and the time of death is critical in criminal proceedings in which there are legal issues of alibi and opportunity to commit the crime.
Thin film appears over the cornea of opened eye within minutes of death (closed eyes- hours)
Immediately following death-body is flaccid, followed by increasing rigidity due to lack of ATP and buildup of lactic acid
Adenosine Triphosphate (ATP)-energy source produced in respiration in mitochondria of cells
In deaths from carbon monoxide poisoning, it is classically described as "cherry red“
In cases where methaemoglobin is formed in the blood during life (e.g. potassium chlorate, nitrates, and aniline poisoning) it appears chocolate brown
In deaths from exposure to cold, it is bright pink, and a similar colouration is seen in bodies refrigerated very soon after death.
Refrigeration of a body already displaying typical purple lividity will cause it to turn pink.
Active Decay Stage
Advanced Decay Stage
Dry Decay Stage
The fresh stage of decomposition is generally described as the period between the moment of death and when the first signs of bloat are apparent.
There are no outward signs of physical change, though internal bacteria have begun to digest organ tissues[.
No odor is associated with the carcass.
Early post-mortem changes, used by pathologists as medical markers for early post-mortem interval estimations; livor mortis, rigor mortis and algor mortis.
The first insects to arrive at decomposing remains are usually Calliphoridae (blow flies), arrive within minutes of death or exposure, and deposit eggs within 1-3 hours.
Flies of the families Sarcophagidae (flesh flies) and Muscidae are also common in this first stage of decomposition.
The first visible sign of the bloat stage is a slight inflation of the abdomen and some blood bubbles at the nose.
Activity of anaerobic bacteria in the abdomen create gases, which accumulate and results in abdominal bloating.
A colour change is observed in the carcass flesh, along with the appearance of marbling.
During the bloat stage the odor of putrefaction becomes noticeable.
First species of Coleoptera arrive, Staphylinidae (rove beetles), Silphidae (carrion beetles) and Cleridae.
These beetles are observed feeding on fly eggs and larvae. Beetle species from the families Histeridae may also be collected during this stage, and are often hidden beneath remains.
Adipocere Also known as "grave wax," adipocere (from the Latin, adipo for fat and cera for wax) is a grayish-white postmortem (after death) matter caused by fat decomposition, which results from hydrolysis and hydrogenation of the lipids (fatty cells) that compose subcutaneous (under the skin) fat tissues.
The beginning of active decay stage is marked by the deflation of the carcass as feeding Dipteran larvae pierce the skin and internal gases are released.
During this stage the carcass has a characteristic wet appearance due to the liquefaction of tissues..
A strong odor of putrefaction is associated with the carcass.
Feeding larvae of Calliphoridae flies are the dominant insect group at carcasses during the active decay stage.
At the beginning of the stage larvae are concentrated in natural orifices, which offer the least resistance to feeding.
Towards later stages, when flesh has been removes from the head and orifices, larvae become more concentrated in the thoracic and abdominal cavities.
Most of the flesh is removed from the carcass during the advanced decay stage, though some flesh may remain in the abdominal cavity.
Strong odors of decomposition begin to fade.
This stage marks the first mass migration of third instarcalliphorid larvae from the carcass Piophilidae larvae may also be collected at this stage.
Few adult calliphoridae are attracted to carcasses in advanced decay.
Adult Dermestidae (skin beetles) arrive at the carcass; adult dermestid beetles may be common, whereas larval stages are not
The final stage of decomposition is dry remains.
Very little remains of the carcass in this stage, mainly bones, cartilage and small bits of dried skin.
There is little to no odor associated with remains.
The greatest number of species are reported to occur in the late decay and dry stages.
The dry decay stage is characterized by the movement from previously dominant carrion fauna to new species.
The dermestid beetles, common in advanced decay, leave the carcass.
Non-carrion insects that commonly arrive at remains in dry decay are centipedes, millipedes, isopods, snails and cockroaches.