Identification of polygonal barrel rifling characteristics in bullet wipe residue deposited on textiles.

This study examines the potential formation of land and groove rifling characteristics in bullet wipe residue deposited on textile fabrics. Textile fabrics comprised of natural, synthetic, semi-synthetic, and blended fibers were damaged either individually or as triplicate layers using two different ammunition types: Winchester WinClean 115 grain 9 mm Luger BEB and Speer 115 grain 9 mm Luger TMJ. Each ammunition type was fired in triplicate using a 9 mm Luger caliber Glock 17 at a distance of approximately 6 feet at normal incidence to the target. The bullet hole was first observed under a stereomicroscope, photographed under tungsten and infrared illumination to observe chemical residues, and subsequently tested for the presence of copper and lead residues. The preliminary chemical results show that land and groove rifling class characteristics can form in bullet wipe residue deposited on textile fabrics. The composition of the fabric, cleanliness of the interior surface of the firearm barrel, presence of intervening layers of fabric, and the bullet type are all potential contributing factors to the detection of rifling characteristics.

Bullet wipe on the uppermost textile layer of gunshot entrance sites: may it be absent due to pre-existing blood staining?

Most gunshot entrance sites on human victims are localized in clothed body regions. Except for the use of lead-free ammunition, a positive color reaction of the sodium rhodizonate test indicates a primary target hit by the bullet. Any lead residue pattern in the area around the entrance hole allows approximate conclusions as to the firing distance in close and intermediate range shots, whereas the presence of a bullet wipe denotes an entrance site. A criminal case gave rise to an experimental study to clarify whether a blood-soaked garment being shot at as a primary target may lack a bullet wipe around the entrance hole. Distant-range shots were fired with a semi-automatic pistol (Heckler & Koch, Mod. USP Compact, cal. 9-mm Luger) using cartridges with jacketed round-nose bullets and a Sinoxid primer containing lead styphnate. In fabrics saturated with fluid blood, a wide area around the bullet entrance was densely covered with rhodizonate-positive microparticles simulating gunshot residues (GSR) from a close-range shot. In shots to fabrics oversaturated with blood, a typical bullet wipe was lacking, whereas lead-containing particles were spotted in the periphery. The results are discussed with respect to the aberrant appearance of bullet entrance sites in blood-soaked fabrics.

Radiodense bullet wipe around osseous entrance gunshot wounds.

"Bullet wipe" is the material deposited by a bullet on any surface with which it comes into contact after it is fired and may contain debris from the gun barrel, including particles of primer and metal fragments from previously fired bullets. X-ray analysis is a non-destructive method by which traces of metallic elements can be visually detected. The analysis of osseous defects for radiodense bullet wipe (RBW) assists in determining the presence or absence of perforating gunshot wounds, especially in fragmented, skeletonized remains. The aim of our current study was to determine the frequency of RBW around entrance firearms injuries that perforated bone. We prospectively analyzed entrance gunshot wounds for RBW over a three-year period using digital X-ray analysis (n = 59). We retrospectively reviewed the corresponding autopsy reports to determine the frequency of RBW by biologic sex, reported ancestry, age-at-death, location of wound, manner of death, range of fire, bullet caliber, and presence of bullet jacket. Data were analyzed by Fisher's exact test or Chi-square test with significance levels accepted at p < 0.05. RBW was present in 66% (n = 39) of examined cases. Decedent characteristics did not significantly alter RBW distribution, including biologic sex (p = 0.75), reported ancestry (p = 0.49), and age-at-death (p = 0.43). Additionally, the location of the osseous entrance gunshot wound, manner of death, range of fire, and cartridge caliber did not affect RBW detection. All cases involving non-jacketed rounds (n = 5) showed RBW (p = 0.30). To our knowledge, this study is the first to report the frequency of RBW detection from osseous entrance gunshot wounds.

Discordance of Gross and Histologic Findings in Estimating the Range of Fire of Gunshot Wounds.

Forensic pathologist use soot and/or stippling surrounding entrance gunshot wounds in categorizing range of fire. If absent, some pathologists suggest utilizing histology when the range is diagnostically critical. This study investigates the concordance of macroscopic and microscopic findings in estimating range of fire by evaluating gunshot entrance and exit wounds made through human tissue analogs at defined distances using two handgun calibers. Examination of over 150 entrance wounds verified the ease of visually detecting soot from a muzzle distance of contact to 1 foot (30.5 cm), and its absence at 9 feet (274.3 cm). Distinctly apparent was bullet wipe surrounding the entrance wounds regardless of muzzle distance. Although variations existed, dark material was histologically identified in many skin, soft tissue, and bone sections at all ranges with both calibers. These nonparallel results decrease the dependability of histology for range of fire estimation and reinforce using gross observation.

Preliminary development of a bleeding layer to assess the effect of a ballistic impact on textile damage.

When a person is shot, they are generally wearing clothing which will be damaged by the perforation of the bullet. There are relatively few reports of such textile damage in the literature and the effect of blood on the textile damage observed is not reported. The appearance of textile damage caused by bullet impacts is further compounded by the diverse nature of (i) fabrics used in apparel and (ii) ammunition types. In this work, the effect of blood on textile damage due to ballistic impact was investigated by the development of a specimen that incorporated blood. The specimens were impacted with two types of pistol ammunition that are commonly available (i) 9mm Luger HP (8.03g; Federal Premium® Law Enforcement; jacketed hollow-point) and (ii) .357 Magnum (10.24g; Express® Pistol and Revolver; Remington, R357M3, flat-nose soft-point). The resulting textile damage was compared to that in specimens without a bleeding layer. The interaction of blood with textile damage caused by a bullet-impact affected the appearance of the textile damage and resulted in the dispersion of the bullet wipe. These results are important in the content of evidence examined by a textile damage assessor compared to what might be seen in a typical re-creation event in a laboratory. The use of a bleeding layer in textile damage investigations due to ballistic impact resulted in a more realistic scenario.

A case of alleged discharge of a firearm within a vehicle.

A road-rage altercation occurred between two vehicle drivers. The driver of vehicle 1 stopped and allegedly fired two shots from within his vehicle over the heads of the driver and passenger of vehicle 2 when they were out of their vehicle. The driver of vehicle 2, an off-duty police officer, fired his .45 calibre pistol at the driver of vehicle 1. The bullet went through the windshield and lodged in the instrument panel. Eight gunshot residue (GSR) samples were taken from the interior of vehicle 1 and analysed by automated scanning electron microscopy/energy dispersive x-ray spectroscopy. The results show for vehicle 1 that a firearm discharged with its breach or cylinder gap within the vehicle was unlikely to have occurred and the .45 calibre bullet which impacted five surfaces of vehicle 1 was accompanied by GSR throughout its travel. A recreational shooter is shown in this study to transfer GSR to the seat of his car. The driver of vehicle 1 visited a recreational gun range prior to the altercation, which would explain the significant GSR contamination of the driver's seat of his vehicle.