Volume 38, Issue 5 (September 1993)
Lead Isotope Ratios in Lead Smears and Bullet Fragments and Application in Firearm Investigations
This paper describes the use of lead isotopes ratios for an investigation of a homicide. Lead smears and bullet fragments recovered from a victim's clothing were compared with lead samples from two suspect bullets.
More than 90 bullets of the same caliber and produced by the same manufacturer as the suspect bullets were analyzed. The lead isotopic compositions were found homogeneous within individual bullets. Different bullets from the same ammunition box also showed indistinguishable lead isotope ratios. Bullets from ammunition boxes produced in 27 different months were analyzed. The results were compared with those obtained for bullets and bullet fragments from the homicide case. The high precision isotope ratio measurements could distinguish between lead from the homicide case and nearly all bullets from the ammunition boxes that were investigated. The isotope ratios for bullets from one of the ammunition boxes were indistinguishable from those for the homicide bullets. Some bullets of the same caliber as the suspect bullets but produced by different manufacturers were also analyzed by this technique. All these bullets showed clear differences in their lead isotope ratios.