AFTE Store - Enhancement of Gunshot Residue Patterns on Dark Colored Fabric Using Sodium Hypochlorite

Since the late 19th century investigators have been using gunshot residue patterns to estimate the muzzle-to-target distance in shooting cases. Given that gunshot residue patterns are difficult to visualize on dark colored clothing, an experiment was conducted by firing .38 caliber bullets at dark and multi-colored cloth at two known distances to test a procedure for enhancing the visualization of gunshot residue patterns. Seven types and colors of fabric tested included: 100% cotton; 65%-35% polyester-cotton; 65%-35% polyester-rayon; and 50%-50% polyester-rayon. After firing into the cloth to produce a gunshot residue pattern, the cloth was treated with a 5.25% solution of sodium hypochlorite to bleach the dye in the cloth and enhance the visualization of the gunshot residue pattern. After treatment, samples of cotton and cotton blend fabrics were tested with the flame atomic absorption spectrophotometer to determine the presence of lead and antimony.