Determination of Firing Distance. Lead Analysis on the Target by Atomic Absorption Spectroscopy (AAS)*
This work has been presented in poster form at the 58th Annual Meeting of the American Academy of Forensic Sciences, Seattle, WA, Feb. 20–25, 2006.
Abstract
Abstract: This paper reports a method for the determination of the firing distance. Atomic absorption spectroscopy (AAS) was used to determine the lead (Pb) pattern around bullet holes produced by shots on test targets from the gun. Test shots were made with a Colt 38 Special at 5, 10, 20, 25, 30, 35, 40, 45, 50, 60, 80, and 100 cm target distance. The target was created with sheets of Whatman no. 1 paper on a polystyrene support. The target was subdivided into three carefully cut out rings (1, 2, and 3; with external diameters of 1.4 cm; 5 cm; 10.2 cm, respectively). Each sample was analyzed with graphite furnace AAS. Lead values analysis performed for each ring yielded a linear relation between the firing distance (cm) and the logarithm of lead amounts (μg/cm2) in definite target areas (areas 2 + 3): [ln dPb2+3 = a0 + a1l]; where dPb2+3 = lead μg/cm2 of area 2 + 3; a0 and a1 are experimentally calculated; l = distance in cm.
