In this x-ray of a coyote, the radio opaque “snow storm” pattern is characteristic of a high powered rifle.  The Pathologist uses the x-ray findings to help in reaching a cause of death diagnosis. Credit: USFWS

PATHOLOGY UNIT

The most obvious objective for a pathological evaluation of a carcass of an animal is to determine the cause of death which for most pathologists means providing a diagnosis.  As we know, multiple diagnoses may be applied to any pathology report depending on the level of investigation which is directly related to the post mortem condition of the carcass.  In legal circles, we refer to the cause, manner, and mechanism of death and we may also list contributory and incidental findings. 

The medical examiner is expected to determine a “cause” of death meaning the disease, injury or abnormality what alone or in combination is responsible for initiating the sequence of functional disturbances that ends in death. This is different than the “mechanism” of death which infers more of the physiological consequence of the injury or disease.  The “manner” of death relates more to the circumstances around the factors that initiated the cause of death with special reference to the social relationship and personal causation.   As the investigating pathologist and an expert witness, you may be asked to explain your opinion on the above designations for the case at hand.

Other objectives which must be considered in a forensic evaluation include the recovery of trace evidence, a reconstruction and documentation of the sequence of events where possible, and an estimation of the time of death.  Trace evidence may include bullets or bullet fragments, tissue or organ samples, stomach and crop contents, carrion feeding insects, hair, etc.  Proper procedures to document the association of the trace evidence items with the original carcass and appropriate preservation and packaging of the trace evidence are also the responsibility of the pathologist.  A chain of custody must be established for each trace evidence item removed from the original carcass.  Photo documentation of the items recovered to demonstrate the origin of the sample or item is an effective way to establish the connection between the carcass and the new trace evidence sample.

For example, a bullet might be photographed in situ with a pointer demonstrating a wound path prior to removing the bullet. Skin samples around a suspected bullet wounds which are removed to demonstrate lead residue or duration of wound should be photographed before and after removal to establish the relationship of the “trace” evidence or sub item to the original sample.  Radiographs (x-rays) are an excellent way to document the presence of bullets, bullet fragments and pellets.  However, field radiographs of large animals are rarely practical.  Metal detectors may be used to demonstrate and recover bullets from carcasses in the field.

For more information, please view our Pathology publications.

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