Differing sizes of bullet entrance holes in skin of the anterior and posterior trunk

The aim of the present study was to establish whether the size (diameter and area) of bullet entrance holes in skin varies between distant shots to the anterior and posterior trunk, respectively, when using the same ammunition (in concreto pistol cartridges 9 mm Luger). For that purpose, specimens of porcine skin from the belly region and the back were taken (10 samples each) and shot at from a distance of 1.6 m. The entrance holes were photo-documented under standardised conditions. After image processing for contrast enhancement, the maximum diameter and the area of each skin defect were measured automatically by means of an image analysis system. Both size parameters differed significantly depending on the body region affected. On the back with its comparatively thick dermis, the skin defects were considerably smaller than those on the ventral trunk where the corium is less thick. This difference can be explained by the fact that the elastic properties of skin are strongly determined by the connective tissue which is especially rich in fibres. The study results were consistent with the authors’ casework experience and support the assumption that the entrance site of gunshot wounds has a major influence on the size of the bullet hole in skin.