The Japanese Association of Science and Technology for Identification

Japanese Journal of Science and Technology for Identification , 8 (1), pp. 89 - 97 , 2003

Possibility of Bullet Identification Using 3D Data

Atsuhiko Banno

Abstract
This study focuses on identification of bullets with three-dimensional data of landmark impressions. Generally, forensic scientists identify bullets by optical tools. For example, a comparison microscope, a CCD camera and photographs etc. Although these approaches are very essential and effective, the appearance of a striation depends on an illumination system in these methods. Therefore, there might remain some problems in the database that consist of only photometric data. On the other hand, 3D data of impressions on fired bullets are expected to possess generality and objectivity for forensic identification because the database that consists of geometric data is perfectly independent of any illumination. In this study, I used a con- focal microscope as a 3D measurement device. I examined two jacketed bullets fired from a 0.25 caliber gun and six jacketed bullets fired from three 0.32 caliber guns. Each bullet had six landmark impressions, and there were twenty-four pairs of landmark impressions to be compared. The texture of a landmark impression is uniform along the direction of the scratch. It is expected that 3D profile is also uniform along the direction, so averaging 3D data along the direction can reduce an influence of measurement error. The averaged profile, shown as a 2D curve, fills the role of a characteristic profile. The 2D comparison of these profiles serves as bullet identification. Minute variations that form vivid striation were not shown clearly because of the averaging procedure. However, the comparisons of 24 pairs made it clear that global shapes of two profiles from the same origin coincide. Therefore, a sectional shape of a landmark impression would be a useful method for bullet identification when the bullet is not deformed and 3D shape of an impression is a little unique.

Keywords: 3D profile comparison, Bullet identification, Con focal optics

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