Cytology on Bullets and Clothing

If a bullet passes through a body or intermediary target, or ricochets off a hard surface, fragments of tissue or target material may adhere to or be imbedded in the bullet. If the bullet is a hollow point, a relatively large wad of this material may be deposited in the cavity. Recovery and identification of foreign material from a bullet may identify the organs or intermediary object perforated or prove that the bullet was a ricochet. Nonorganic material, such as aluminum from a window screen perforated by a bullet or minerals from a stone off of which a bullet ricocheted, can be identified on a bullet by SEM-EDX.6

If a bullet is found at a scene, or if multiple bullets are found in a body cavity after perforating different organs, it might be possible to determine that the bullet at the scene perforated a body or to determine which bullet recovered from a body cavity perforated which organ. If the bullet perforated bone and particles of bone were deposited on/in the bullet, identification of this bone can be made by histological examination if the fragment is large enough, or if too small, by SEM-EDX. Thatabulletperforatedtissueor even a specific organ may be determined bycytologicalmeans. Nicholsand Sens have described a method of recoveryandidentificationof tissueand foreign material too small to visualize.7 This process involves rinsing unwashed recovered bullets in various solutions, filtering the solutions through a cytology filter, and then performing cytologic staining on the material. In the case of high-velocity bullets, they noted extensive fragmentation of the tissue with blood clots, bone fragments, muscle, and amorphous debris, the most common tissues recovered. Mesothelial cells and organ fragments were less common. Tissue recovered from low-velocity bullets was better preserved and more abundant. Adipose tissue, fragments of small vessels, clumps of spindle cells were most commonly found; skeletal and cardiac muscle, occasionally. Visceral organ fragments were not necessarily found even when the organs were perforated. Skin was the least commonly encountered. In regard to gunshot wounds of the head, bone chips, skeletal muscle, connective tissue, and strips of small vessels were commonly identified. Fragments of brain were present but were not readily recognizable as neural in origin.

In numerous cytologic preparations, black deposits, most likely representing soot and/or debris from the barrel, were present irrespective of the range, i.e., distant or close-range. If the bullet perforated clothing, fibers were commonly found.

While blood from the victim is often searched for on the clothing of the alleged perpetrator, it is not appreciated that in contact wounds of the head, brain tissue may be blown back on the perpetrator's clothing. The stains produced do not resemble blood but rather coffee or soft drink stains. If these areas are soaked in saline solution, cellular material may be extracted from the cloth. Brain tissue can then be identified by cytological methods.

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