Firearm projectile collection techniques: A comparative study on the retention of textile fibers adhered during projectile perforation of denim fabric

Trace evidence plays a critical role in forensic reconstructions, especially when involving microscopic materials transferred during projectile impacts. This study investigated the adherence of blue jeans fibers to 9 mm caliber projectiles, evaluating six projectile collection methods—PVC tube filled with cotton, PVC tube filled with cotton waste, water tank, ballistic vest plates (Kevlar®), combination of cardboard and ballistic plates, and motorcycle tire combined with ballistic plates—and comparing two ammunition types: hollow-point (HP) and full metal jacket (FMJ). Digital microscopy enabled high-resolution, non-destructive analysis of fiber adherence. HP projectiles retained blue jeans fibers in 94.4 % of cases, significantly more than FMJ projectiles (22.2 %), with a highly significant association. Fiber presence was most frequently observed at the projectile tip and within the HP cavity. Barriers using cotton provided optimal conditions for fiber preservation and minimal visual contamination, whereas water tanks caused fragmentation in HP projectiles and the other materials resulted in considerable deformation and visual contamination, hindering analysis. These findings confirm the superior capacity of HP projectiles to retain microtraces and establish cotton-filled PVC tubes as an effective method for ballistic evidence recovery. Therefore, the use of hollow-point projectiles combined with the cotton-filled PVC tube collection technique is recommended for ballistic tests involving textile microtrace analysis. The study also emphasizes that the absence of visible fibers should not be interpreted as a lack of fabric interaction.