TECHNICAL NOTE ANTHROPOLOGY; CRIMINALISTICS Hugh E. Berryman, 1 Ph.D.; Alicja K. Kutyla, 2 M.S.; and J. . Russell Davis, II, 3 B.S. Detection of Gunshot Primer Residue on Bone in an Experimental Setting—An Unexpected Finding* ABSTRACT: Pork ribs with intact muscle tissue were used in an experimental attempt to identify bullet wipe on bone at distances from 1 to 6 feet with 0.45 caliber, full metal jacket ammunition. This resulted in the unexpected finding of primer-derived gunshot residue (GSR) deep within the wound tract. Of significance is the fact that the GSR was deposited on the bone, under the periosteum, after the bullet passed through a Ziploc Ò bag and c. 1 inch of muscle tissue. It is also important to note that the GSR persisted on the bone after the periosteum was forcibly removed. The presence of primer-derived GSR on bone provides the potential to differentiate gunshot trauma from blunt trauma when the bone presents an atypical gunshot wound. In this study, the presence of gunshot primer residue at a distance of 6 feet demonstrates the potential for establishing maximum gun-to-target distance for remote shootings. KEYWORDS: forensic science, gunshot residue, SEM-EDX, forensic anthropology, gunshot trauma, ballistics, firearms examination A recent skeletal forensic case presented a fractured rib with a missing segment suspected to be a gunshot wound, but the frac- ture lacked the typical bevel associated with a bullet. In an attempt to verify that a bullet produced the trauma, a scanning electron microscope (SEM) equipped with an energy dispersive X-Ray analyzer (EDX), was used to visually and compositionally examine the bone for lead or other metals commonly associated with bullet wipe (i.e., residual bullet trace). No bullet wipe was found, leading the authors to design a study to determine how metal from a bullet would appear on experimentally shot bone using SEM-EDX. Round nose lead and copper jacketed bullets were used with the expectation of seeing bullet wipe in the form of a metallic streak. Although bullet wipe could not be detected on the experimentally shot bone, particles in high concentration were observed over the bone surface, even at some distance away from the fracture site. Upon EDX analysis of these areas trace amounts of lead (Pb), barium (Ba), and antimony (Sb)—compo- nents of a bullet primer—were detected. The original purpose for this research was revised to demonstrate that primer-derived gun- shot residue (GSR) can be detected on bone deep within a wound track. Pork ribs were selected as they were readily accessible and provided the simulation of a deep wound tract, as at least 1 inch of muscle tissue overlaid each bone. Scanning electron microscopy has long been used for obtaining images with resolution and depth of field superior to those of light microscopy. The primary sample requirement is to be stable under vacuum while the surface is being scanned with an electron beam. Interactions of the beam of electrons with the surface of the sample produce a number of signals, each of which are useful and have their own separate detector. Secondary and backscatter electron sig- nals are primarily used for imaging, backscatter differing in that they are higher energy and can be useful in screening higher atomic mass areas from lower atomic mass areas. Characteristic x-rays are also produced by the electron bombardment. These can be measured simultaneously and allow identification of virtually every element on the periodic chart. Scanning electron microscopy in combination with energy dispersive x-ray spectrometry is a very powerful analytical instrument for materials analysis and is extre- mely useful in the forensic application at hand. Discharge of a firearm begins when the primer is crushed by the firing pin driving hot gases and burning particles into the propellant (1,2). Ignition of the propellant occurs within a matter of a few ten thousands of a second and the high pressure from the heated gases propels the bullet out of the cartridge casing (1,2). Primer vapors are created through this reaction and condense into droplets form- ing gunshot primer residue (1,2). Primer condensation particles are comprised mainly of Pb, Ba, and Sb and can contain elements such as aluminum (Al), silicon (Si), sulfur (S), potassium (K), and cal- cium (Ca) that can originate from sources such as etched bullets, cartridge casings, or barrels (1,2). According to Meng and Caddy (1) ‘‘When a gun has been fired, gunshot residues can arise from the primer, propellant, lubricants, and metals that are found in the bullet, bullet jacket, cartridge cas- ing, and gun barrel. ’’ Within forensic literature the term ‘‘gunshot residue’’ has been used to describe virtually any material exiting a fired weapon. For the purpose of this technical note, the authors wish to make clear that the materials being discussed are only and 1 Director, Forensic Institute for Research and Education, Middle Tennes- see State University, Murfreesboro, TN. 2 Department of Anthropology, University of Tennessee at Knoxville, Knoxville, TN. 3 Special Agent Forensic Scientist, Tennessee Bureau of Investigation, Nashville, TN. *Presented at the 60th Annual Meeting of the American Academy of Forensic Sciences, February 18–23, 2008, in Washington, DC. This paper received the Physical Anthropology Section’s Ellis R. Kerley Award. Received 8 Nov. 2008; and in revised form 11 Jan. 2009; accepted 31 Jan. 2009. J Forensic Sci, March 2010, Vol. 55, No. 2 doi: 10.1111/j.1556-4029.2009.01264.x Available online at: interscience.wiley.com 488 Ó 2010 American Academy of Forensic Sciences