Distinctive bullet impact holes by 9-mm caliber projectile on sheet metal surfaces

Abstract

Introduction: A comprehensive scene reconstruction requires forensic investigators to examine the impact marks left on various surfaces to identify whether a projectile produces a specific hole. Subsequently, it is further necessary to determine whether a particular ammunition has caused the impact. Throughout history, designs of ammunition have evolved with the intended effects, which could leave different impact marks on a target surface, especially by ammunition with a nonconventional design. Careful examination on impact marks and determination of their specific characteristics on sheet metal of vehicle would provide crucial forensic information. Aim: This study was aimed to physically characterize bullet impact holes made by 11 types of 9-mm caliber ammunitions. Materials and Methods: Two automotive doors were shot with different ammunitions from the same firearm, and the morphological features of bullet impact holes were observed and compared. Results: Bullet impact holes produced by the various ammunitions could be differentiated through careful observation of bullet hole circumferences, presence of petalling effect, metallic ring and triangular peak at the edge, and deposition of residue at the peripheral area of bullet impact holes. Ammunitions with nonconventional design such as Inceptor-Polycase and GECO Hexagon showed observable morphological differences and discriminated them from bullet impact holes made by conventional ammunitions. Conclusion: A thorough physical examination could aid in distinguishing bullet impact holes and predicting the possible types of ammunition that had made an impact hole on a surface.