Macroscopic,Microscopic, and Chemical Assessment of Gunshot Lesions on Decomposed Pig Skin

Abstract: Very little literature exists on gunshot wounds on decomposed material. In this study, seven pig heads underwent a shooting test. Entrance wounds from the first head underwent neutron activation analysis (NAA) and histological testing immediately after the firing test; the other six heads were exposed to two different environments (open air and soil) and analyzed by radiochemical and histological tests every 15 days. Gunshot wounds in air maintained their morphological characteristics, and those in soil showed severe alteration after 5 weeks. Microscopic testing verified positive results for lead in all gunshot wounds in open air, whereas in most of those in soil lead could not be detected. Radiochemical analysis performed by NAA yielded for all gunshot wounds but one antimony quantities in the range of 0.07–13.89 μg. In conclusion, it may be possible to detect residues of antimony even in degraded tissues.     

X-ray mapping technique: a preliminary study in discriminating gunshot residue particles from aggregates of environmental occupational origin

The possibility of detection of lead-antimony-barium aggregates from non-firearm sources is confirmed according to the tests performed on brake pads, and firework and automobile workers. Moreover, information on particles taken from cartridge cases shows the relative feeble importance of the morphology in distinguishing gunshot residues (GSRs). Furthermore, also the presence in the spectrum of other elements (e.g., iron) is not so conclusive. In this panorama, the possibility of discriminating gunshot residue particles from other non-firearm lead-antimony-barium aggregates is investigated: the proposed method is based on X-ray mapping technique--currently applied used in Reparto Carabinieri Investigazioni Scientifiche in Rome, the forensic service of Italian Carabinieri--according to which the spatial distribution of the emission energy of each element of the sample is pictured. Gunshot residues present the same lead-antimony-barium distribution (or at least the same antimony-barium distribution with lead nodules), as some other environmental occupational aggregates do not (different plaques of lead, antimony, and barium). So, X-ray mapping technique can offer a new fundamental evaluation parameter in analysis of gunshot residues with scanning electron microscopy/energy-dispersive (SEM/EDS) spectrometry, and new standards could be considered.     

Gunshot residues on dry bone after decomposition-a pilot study

Abstract: Very little literature exists concerning radiochemical and microscopic analyses of gunshot wounds in decomposed material, and even less concerning skeletonized samples; the most advanced technologies may provide useful indications for the diagnosis of suspect lesions, especially if gunshot wounds are no longer recognizable. However, we know very little of the survival of gunshot residues (GSR) in skeletonized samples. This study examined nine gunshot wounds produced on pig heads which then underwent skeletonization for 4 years, and four gunshot entries on human heads from judicial cases which were then macerated to the bone in water; the samples underwent scanning electron microscopy coupled with energy dispersive X‐ray (SEM‐EDX) analysis. Positive results for GSR were observed only in four of the nine animal samples and in all four human samples. Among the human samples, two lesions showed Pb and Sb, one lesion only Pb, and one Pb, Sb, and Ba. This pilot study showed the survival of GSR in skeletal material and therefore the crucial importance of SEM‐EDX analyses on skeletonized material. Further studies are needed in order to ascertain the role of environmental modifications of GSR.     

Postmortem Computed Tomography and Magnetic Resonance Imaging of Gunshot Wounds to the Neck

Postmortem magnetic resonance imaging (MRI) is rarely used for the radiologic assessment of gunshot injuries, although it has clear advantages over postmortem computed tomography (CT) with regard to the imaging of soft tissue injuries. Another benefit in using MRI is that lodged projectiles composed of nonferromagnetic material such as lead present only marginal metal artifacts compared with severe artifacts on CT. This case report presents CT and MRI findings in a case with two gunshot wounds to the neck: a perforating wound and a nonperforating wound with a lead bullet lodged in the cervical spine. The decedent underwent CT and MRI before the scheduled autopsy. A ring of radiopaque material under the dermis in the fatty tissue was identified at both entrance wounds on CT, which was indicative of contact shots. The perforating gunshot was clearly indicated on CT by bullet fragments along the wound channel through the perforated 6th cervical vertebra and the fractured cricoid cartilage at the exit wound. The second trajectory, however, was only assumed based on the presence of gunshot residues at the entrance wound and the position of the lodged bullet. The radiologic assessment was severely impeded by the metal artifacts on CT. Barely noticeable metal artifacts on MRI allowed for clear visualization of the soft tissue injuries and the ruptured medulla oblongata. Only MRI clarified the soft tissue injuries of the brainstem noninvasively, which could provide specific and graphic information on the rapidity of death and the incapacitation of the victim.     

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.     

Comparison of Different Swabs for Sampling Inorganic Gunshot Residue from Gunshot Wounds: Applicability and Reliability for the Determination of Firing Distance

This study concentrates on samples of bare pork skin, with and without bristles, and dried bovine ribs shot with a semi‐automatic pistol to find the best methodology and sampling surface in the search for inorganic gunshot residues (IGSR). Four quadrants of known surface areas were sampled at different distances from the bullet's hole with different swabs: tapes in graphite, Leukosilk® white tape, 3M® transparent tape, and a cotton swab to assess the technique able to collect the highest amounts of IGSR with the lowest contribution of the blank. The cotton swab wet in 10% HNO₃ gave the best results. The highest amounts of IGSR, measured by ICP‐OES and MS, were detected on a surface of 3‐cm radius from the bullet's edge. The amount of metals collected decreased with the firing distance between 20 and 60 cm. The procedure was efficient for sampling different tissues like skin and bones.     

Characteristics and Frequency of Chipping Effects in Near‐Contact Gunshot Wounds

The presence of “chipping” or “flaking” around the edges of gunshot entry wounds has been described among the characteristics of gunshot wounds in bone. In this study, the real frequency of such a peculiar feature was investigated. The presence of “chipping” was assessed on 22 gunshot wounds fired at a near‐contact range on bovine ribs with 9‐mm bullets. As controls, five samples were shot with a 3 cm range, and five from 40 cm. In 77% of cases shot at near‐contact range, a detachment of small fragments of the upper layers of bone was detected, mainly with a circumferential disposition, whereas this feature was lacking in control samples. The study demonstrated the frequency of “chipping” and that it may probably be due to a combined ballistic effect of impact of the bullet itself and expansion of gases. It may be thus considered indicative of close‐range shots.     

Soft tissue radiography in determining contact and near-contact gunshot wounds.

Contact and near-contact gunshot wounds ordinarily show distinctive gunpowder patterns, muzzle imprints, or tearing of the skin. Microscopic and chemical examination have been used to estimate firing distances. A new method that utilizes soft tissue radiography is described. Nonjacketed lead bullets deposit a pattern of fragments and residues in tissue circumscribing contact and close gunshot wounds. Various patterns are presented to contrast the appearance of contact from distant gunshot wounds using various firearms and different types of bullets. This procedure may be used as an adjunct in the determination of contact and close gunshot wounds.     

A method for collection of gunshot residues from skin and other surfaces

A method of collecting gunshot residues from the skin of persons who have been injured by firearms has been developed. The method uses a commercially available, adhesive, transparent plastic film. This method is also useful for collecting gunshot residues from other objects, such as leather. The shooting distance is later estimated by ocular, microscopic or IR examination in combination with various chemographic tests.     

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^® 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.     

Fatalities from black powder percussion handguns

Three suicides and one homicide from black powder muzzle loading handguns are reported and the muzzle velocities of two weapons are recorded. The fatal head shots caused wide wound tracts traversing the brains and intracerebral haemorrhages remote from the tract were present in every case. The skulls showed considerable fractures which were pronounced in the cases of contact shots but were also present when the range of fire was 5 m. These extensive injuries from soft lead spheres with muzzle velocities of only ∼200 m/s are attributed to the expansion of the spheres. The regularly occurring deformation resulted in 13–16 mm calibre missiles in the cases of .44 spheres. The special features of black powder such as incomplete and slow combustion resulted in intense soot deposits in the vicinity of the entrance wound and in long ranges the gunshot residues travelled. In contact shots, large pocket-like underminings even in deeper tissue layers, abundant soot along the trajectory and skin burns were observed.     

The use of a tunable light source (Mini-Crimescope MCS-400, SPEX Forensics) in dissecting microscopic detection of cryptic epithelial particles

As skin particles are often deposited by even a single skin contact, the detection of skin debris is important for evidence collection and DNA testing. Unfortunately, even when a dissecting microscope is used by an experienced examiner, epidermal particles are often hard to find and these traces of evidence might escape DNA analysis. Fluorescence is defined as the property of absorbing short-wavelength light and emitting longer-wavelength light. By virtue of the fluorescence characteristics of many target materials, tunable light sources assist in the macroscopic search of crime scenes and items. We combined the dissecting microscope and an alternate light source to examine the fluorescence characteristics of skin and skin particles. In a comparative study, small skin scales were hidden between sand, fibers, and soil probes, and it proved possible to search more successfully with less time and effort. On staged casework exhibits, the efficiency of the screening aid was again tested and the usability of the new procedure shown.     

Differential pulse anodic stripping voltammetry of barium and lead in gunshot residues

Differential pulse anodic stripping voltammetry (DPASV) has been applied for characterization and quantitative detection of barium and lead from gunshot residues (GSR). Previous electrochemical techniques have detected antimony and lead from GSR, however barium has never been detected. This technique allows for simultaneous detection of Ba and Pb that is simple, fast, and nondestructive.     

Gunshot residue patterns on skin in angled contact and near contact gunshot wounds

The goal of this study was the reproduction of shape and pattern of gunshot residues in near contact and contact gunshot wounds by a series of experimental gunshots on a skin and soft tissue model. The aim was to investigate the shape and direction of soot deposits with regard to the muzzle according to different muzzle-target angles, firing distances, type of ammunition and weapon and barrel length. Based on a review of the literature and on the results of the experiments the authors could make the following statements of gunshot residues in angled contact and close contact gunshot: (1) gunshot residues on the target surface can be differentiated in a "inner" and "outer powder soot zone"; (2) the outer powder soot zone is much less visible than the inner powder soot zone and may lack on human skin; (3) with increasing muzzle target distance both inner and outer powder soot halo increase in size and decrease in density; (4) in angled shots the inner powder soot halo shows an eccentric, elliptic shape which points towards the muzzle, regardless of ammunition, calibre and barrel length; (5) the outer powder soot points away from the muzzle in angled contact and close contact shots.     

A Rare Case of an Intact Bone Plug Associated with a Gunshot Exit Wound

This case study presents an unusual manifestation of gunshot trauma in skeletal tissue from a post‐World War II human rights abuse sample uncovered in Vilnius, Lithuania. After briefly reviewing the typical wound appearance of projectile trauma in the cranium, we discuss the presence of an intact bone plug associated with a gunshot exit wound in an individual from the Tuskulenai Case. While this individual demonstrated typical gunshot entry and exit wounds to the cranium consistent with high‐velocity trauma, the bone plug indicates that the projectile likely lost much of its kinetic energy while traveling through the cranium resulting in a low‐velocity impact at the exit site. This study reviews a similar instance of a bone plug recovered from a bioarcheological sample in Peru and emphasizes the importance of thorough archeological excavations of mass graves.     

Controversial Suicide Case Using a Submachine Gun with a Sound Suppressor—The Need of Team Work of Forensic Chemistry and Firearm Examiners

Evidence materials in a presumed suicide case were studied by a firearm examiner and a forensic chemist. The victim's body with double gunshot wounding in his forehead, a machine gun in the sustained fire mode with a silencer, and four cartridge cases were found. Examinations of the evidence, the case file studies, and experiments dedicated to the case were carried out. Relationships between the placement of cartridge cases and the gun were established using a fast camera. The distributions of gunshot residues on the evidence materials and within the comparative gunshot patterns were studied by means of optical and electron microscopy, X‐ray microanalysis, and infrared spectroscopy. The shooting distance was assessed to be 30 cm or more, whereas the greatest distance that could have been achieved by the victim himself was about 11–13 cm. The obtained results supported the version of homicide rather than suicide.     

Analysis of primer residue from lead free ammunition by X-ray microfluorescence

In forensic science, the analysis of gunshot residues was traditionally done by the detection of lead (Pb), antimony (Sb) and barium (Ba) usually found in a primer. However, the recent development of lead-free ammunition represents a new challenge for ballistic specialists. This analysis study gunshot residues from primers and ammunitions in the area surrounding bullet holes, a very important tool to determine the shooting distance. The ammunitions used were 9 mm Luger and .38 spl + p calibers, where lead in the primer was replaced with strontium (Sr) and where the lead bullet was plated with copper (Total Metal Jacket). Gunshot analysis results were obtained using an energy dispersive X-ray microfluorescence spectrometer. The method allows the detection and quantification of strontium residues on the target up to a distance of 45 cm.     

Image analysis of gunshot residue on entry wounds: I – The technique and preliminary study

An automated image analysis (IA) technique has been developed to obtain a measure of the amount (i.e. number and area) of gunshot residue (GSR) particles within and around a gunshot wound. Sample preparation and IA procedures were standardised to improve the reproducibility of the IA measurements of GSR. Measurements of GSR from test firings into goat hide were enhanced by staining the barium and lead components present on the skin sections with Alizarin Red S. The amount of GSR detected on the stained skin sections was compared with backscatter electron micrographs of the same sections. The differences were deemed to be insignificant when the variability in the repeated test firings were taken into consideration. Preliminary results indicated that the decreasing relationship between firing range and the amount of GSR deposited was non-linear, and that for firing ranges of up to 20 cm the amount of GSR deposited from repeated shots fired from the same distance was highly variable.     

Image analysis of gunshot residue on entry wounds. I--The technique and preliminary study.

An automated image analysis (IA) technique has been developed to obtain a measure of the amount (i.e. number and area) of gunshot residue (GSR) particles within and around a gunshot wound. Sample preparation and IA procedures were standardised to improve the reproducibility of the IA measurements of GSR. Measurements of GSR from test firings into goat hide were enhanced by staining the barium and lead components present on the skin sections with Alizarin Red S. The amount of GSR detected on the stained skin sections was compared with backscatter electron micrographs of the same sections. The differences were deemed to be insignificant when the variability in the repeated test firings were taken into consideration. Preliminary results indicated that the decreasing relationship between firing range and the amount of GSR deposited was non-linear, and that for firing ranges of up to 20 cm the amount of GSR deposited from repeated shots fired from the same distance was highly variable.     

92式手枪射击距离与射击残留物分布密度相关性的研究

目的研究92式手枪射击距离与射击残留物分布密度的相关性,为射击距离的推断提供依据。方法选择92式手枪,在带皮的猪肉上覆盖白色棉布,设计了0m,0．1m,0．2m,0．5m,1．0m,1．5m,3．0m,5．0m,10m,15．0m,20．0m,25．0m共12个距离进行射击,提取白棉布上的弹孔圆周和距弹孔2cm的圆周上的射击残留物,利用扫描电镜／能谱仪对不同射击距离遗留在白棉布上的射击残留物进行检验。结果白棉布上射击残留物分布密度与射击距离呈负相关的关系。结论根据棉布上射击残留物的分布密度,能够推断射击距离,对涉枪案件中射击距离的判断有一定的参考价值。