Firing distance estimation through the analysis of the gunshot residue deposit pattern around the bullet entrance hole by inductively coupled plasma-mass spectrometry: an experimental study

The use of inductively coupled plasma-mass spectrometry (ICP-MS) in the study of gunshot residues (GSR) is relatively recent, and only a few studies have been published on the subject. In the present paper, this instrumental technique has been used to study the deposit pattern of the GSR around the bullet entrance hole, through the analysis of antimony (Sb), barium (Ba), and lead (Pb). The data obtained were used to establish a mathematical model for estimating the firing distance. Test shots using a 6.35-mm pistol were made against a target of cotton tissue, and the amounts of Sb, Ba, and Pb deposited in quadrangular pieces of the target, cut from 4 radial positions, were determined by ICP-MS. In these experimental conditions, it was possible to estimate the firing distance on the interval [20-80] cm. The best linear correlation between ln m and d, where m is the mass of Sb, Ba, or Pb in the samples, expressed in mug/g of target tissue, and d the firing distance, was obtained at radial distances between 3.5 cm and 4.5 cm from the entrance hole. The best regression curve which adjusted to the data was a linear multiple regression between the firing distance and the logarithm of the mass of each element: d = a + b(1)X(1) + b(2)X(2) + b(3)X(3), where X(1) = ln m (Sb), X(2) = ln m(Ba) and X(3) = ln m (Pb). The accuracy of firing distance estimation using only 1 or 2 elements was not significantly different from the one obtained with the 3 elements.     

Detection of Pb,Ba, and Sb in Cadaveric Maggots and Pupae by ICP-MS*

The concentrations of lead (Pb), barium (Ba), and antimony (Sb), characteristic of GSR, were determined in soil sediments and immature (larvae) of cadaveric flies of the family Calliphoridae, by inductively coupled plasma mass spectrometry (ICP-MS). This research refers to a case study from two real crime scenes in which the corpses were in an advanced state of decomposition. In case 1, the victim had holes similar to gunshot wounds, and in case 2, there was no evidence of perforations in the corpse. Soil sediment collection was performed at three different points of the terrain, at a minimum distance of 10 m from the corpse, for cases 1 and 2. In relation to the collection of immatures, larvae were collected in regions of the mouth, nose, and orifices similar to the entry of firearms projectile into the body, for case 1, and collection of larvae and pupae, located on the body and underneath it, for case 2. It was possible to detect and quantify the three elements of interest (Pb, Ba, and Sb) by ICP-MS in both sediment and cadaveric larvae. Concentrations of 4.44, 8.74, and 0.08 μg/g were obtained for Pb, Ba, and Sb, respectively, in the soil for case 1. For the case 2, the concentrations in Pb, Ba, and Sb were from 16.34 to 26.02 μg/g; from 32.64 to 57.97 μg/g and from 0.042 to 0.30 μg/g, respectively. In the larvae, Pb, Ba, and Sb were quantified in cases 1 and 2 with a concentration of 6.28 and 1.78 μg/g for Pb, 1.49 and 2.94 μg/g for Ba, 0.50 μg/g and <LD for Sb, respectively. These new results present the detection of characteristic elements of GSR in cadaveric larvae in humans in a real crime scene, besides highlighting the importance of the study of immature flies, using the ICP-MS technique in forensic analysis.     

Primer residue analysis of ammunition of Indian origin by neutron activation analysis

The primer residues of ammunition manufactured in India have been analysed by neutron activation analysis (NAA). Since NAA is rather insensitive for lead, attention was confined to the elements antimony, barium, copper and mercury. The element/element combinations detected in significant amounts were (Sb), (Ba, Hg), (Ba, Cu, Sb), (Cu, Hg, Sb) and (Hg, Sb). The present study reveals the presence of Hg from mercury fulminate in priming compositions long discontinued in most ammunition of foreign origin. The presence of Hg can be advantageous in certain situations where the matrix on which the residue is deposited contains high levels of antimony such as clothing made of synthetic fibres. Caution is also required in interpreting the Cu values as being solely due to a jacketed projectile.     

Differentiation of bullet type based on the analysis of gunshot residue using inductively coupled plasma mass spectrometry

Porcine tissue samples shot with two different types of bullets, jacketed and nonjacketed, were collected in the fresh state and throughout moderate decomposition. Wound samples were microwave-digested and analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to detect all elements present at measurable levels in gunshot residue (GSR). Elements detected included antimony (Sb), barium (Ba), and lead (Pb), which are considered characteristic of GSR, as well as iron (Fe) and copper (Cu). These five elements were used to differentiate shot tissue and unshot tissue, as well as tissue shot by the two different bullet types, both in the fresh state and throughout moderate decomposition. The concentrations of Cu, Sb, and Pb were able to distinguish the two bullet types in fresh tissue samples at the 95% confidence level. Cu and Pb were able to differentiate the bullet types throughout moderate decomposition at the 99% confidence level.     

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.     

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.     

A new method for collection and identification of gunshot residues from the hands of shooters

This work presents a novel collection method for gunshot residues (GSR) using a sampling procedure based on ethylenediaminetetraacetic acid (EDTA) solution as a complexing agent on moistened swabs. Detection was via a sector-field inductively coupled plasma mass spectrometry (HRICP-MS). The proposed collection and analytical method allowed detection of antimony (Sb), barium (Ba) and lead (Pb) after .38 shot tests. at detection limits of less than 1 microg L(-1) in four different areas of the hands of volunteers. This paper includes a discussion concerning hand areas near the thumb and forefinger as being more suitable for GSR collection as well as a comparison between differences observed using 2% diluted EDTA. 2% nitric acid solution, and simple deionized water as collecting solutions, proving the superior efficiency of EDTA in GSR recoveries.     

Levels of trace and major elements in illicit heroin

Ten elements, aluminum (Al), barium (Ba), calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), lead (Pb), and zinc (Zn) were analyzed in 44 illicit heroin samples from Southeast Anatolia, Turkey. Illicit heroin samples were dissolved in nitric acid using microwave oven and were quantified by electrothermal atomic absorption spectrometry (Cd and Pb) and inductively coupled plasma-atomic emission spectrometry (Al, Ba, Ca, Cu, Fe, Mg, Mn, and Zn). The most abundant element was calcium, 4050 to 14,200 microg/g, which could be ascribed to the use of lime in the manufacturing process and/or as diluting agent. Iron (180 to 1470 microg/g), aluminum (42 to 2280 microg/g), and zinc (160 to 210 microg/g) were found at moderately high levels, possibly because of the use of metal pots in the acetic anhydride cooking process and also for storage. Cadmium and lead concentrations were at the lowest measured levels. The amounts of magnesium, manganese, barium, and copper were in the range of 100 to 800 micro/g, 3 to 17 microg/g, 4 to 30 microg/g, and 2 to 46 microg/g, respectively.     

Forensic veterinary radiology: ballistic-radiological 3D computertomographic reconstruction of an illegal lynx shooting in Switzerland

The most popular handgun in Brazil is the single round-barrel caliber 0.38 revolver. In recent years, however, owing to the modernization of police arms and their availability on the legal and illicit markets, pistols have become increasingly popular and currently represent about 20% of police seizures. In a previous paper we presented a novel collection method for gunshot residues (GSR) using a sampling procedure based on ethylenediamine-tetraacetic acid (EDTA) solution as a complexing agent on moistened swabs with subsequent detection using sector field-high resolution-inductively coupled plasma-mass spectrometry (SF-HR-ICP-MS). In the present paper, we discuss the capability of this methodology to identify antimony (Sb), barium (Ba) and lead (Pb) on the hands of volunteers after shot tests with 9 mm and 0.40 in. caliber pistols. Two types of munitions were tested: 9 mm Taurus and clean range. The use of a technique with high sensitivity, such as SF-HR-ICP-MS, permits the identification of low concentrations (less than 1 microg/L) of metals in firearm residue and constitutes a powerful tool in forensic science. We also discuss the importance of the sampling procedure, including collection from a different body part than the gun hand of the suspect. Comparison of the analytical data obtained allows clear discrimination between samples from the hands of shooters and non-shooters.     

Crime scene investigations using portable,non-destructive space exploration technology

The National Institute of Justice (NIJ) and the National Aeronautics and Space Administration's (NASAs) Goddard Space Flight Center (GSFC) have teamed up to explore the use of NASA developed technologies to help criminal justice agencies and professionals solve crimes. The objective of the program is to produce instruments and communication networks that have application within both NASA's space program and NIJ programs with state and local forensic laboratories. A working group of NASA scientists and law enforcement professionals has been established to develop and implement a feasibility demonstration program. Specifically, the group has focused its efforts on identifying gunpowder and primer residue, blood, and semen at crime scenes. Non-destructive elemental composition identification methods are carried out using portable X-ray fluorescence (XRF) systems. These systems are similar to those being developed for planetary exploration programs. A breadboard model of a portable XRF system has been constructed for these tests using room temperature silicon and cadmium-zinc telluride (CZT) detectors. Preliminary tests have been completed with gunshot residue (GSR), blood-spatter and semen samples. Many of the element composition lines have been identified. Studies to determine the minimum detectable limits needed for the analyses of GSR, blood and semen in the crime scene environment have been initiated and preliminary results obtained. Furthermore, a database made up of the inorganic composition of GSR is being developed. Using data obtained from the open literature of the elemental composition of barium (Ba) and antimony (Sb) in handswipes of GSR, we believe that there may be a unique GSR signature based on the Sb to Ba ratio.     

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.     

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.     

Glass-containing gunshot residue particles: a new type of highly characteristic particle?

In 0.22 caliber rimfire ammunition, the primer often contains lead or lead and barium compounds. As residues from these primers do not contain lead, barium, and antimony, they cannot be uniquely classified as gunshot residue (GSR) under ASTM designation E 1588-95. In many types of 0.22 caliber rimfire ammunition, the cartridge contains a primer sensitized with glass. In this paper we describe a previously unreported type of GSR particle consisting of glass fused with other primer components. As there appear to be few potential environmental or occupational sources of particles composed of lead and barium compounds fused to glass, particularly borosilicate glass, these particles may have high evidential value. Scanning electron microscopy with energy dispersive X-ray detection (SEM-EDX) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) were evaluated for the characterization of glass-containing GSR particles. The occurrence of glass-containing GSR particles was established in the residue from various brands of 0.22 caliber ammunition, and several sub-types were identified.     

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.     

Does the Prior Application of the Field Kit Bullet Hole Testing Kit 3 on a Suspected Bullet Hole Bias the Analysis of Atomic Absorption Spectrophotometry?

Forensic ballistics is the study of bullet trajectory and consists of determining gunshot residue (GSR) to identify bullet holes. Among several highly sensitive methods, atomic absorption spectrophotometry (AAS) is employed to analyze GSR in the laboratory. However, it is sometimes necessary to identify bullet holes immediately at a crime scene. The purpose of this examination was to determine whether the use of the field test Bullet Hole Testing Kit 3 (BTK3) on a suspected bullet hole would influence the outcome of AAS‐analysis: Three commonly encountered firearms (Glock17, Tokarev, and Colt) were fired at skin, wood, and cloth. AAS‐analysis was performed with and without previous BTK3 application. The results clearly indicate that there is no significant interaction on the grounds of BTK3 use (BTK3 vs. no‐BTK3 [kit_nokit] [Pb: p = 0.1309; Sb: p = 0.9111], material*kit_nokit [Pb: p = 0.5960; Sb: p = 0.9930], distance*kit_nokit [Pb: p = 0.4014; Sb: p = 0.9184], and firearm type*kit_nokit [Pb: p = 0.9662; Sb: p = 0.9885]); hence, applying this field kit does not falsify later AAS outcomes.     

A simple method for detection of gunshot residue particles from hands, hair, face, and clothing using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX).

We devised a simple and rapid method for detection of gunshot residue (GSR) particles, using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX) analysis. Experiments were done on samples containing GSR particles obtained from hands, hair, face, and clothing, using double-sided adhesive coated aluminum stubs (tape-lift method). SEM/WDX analyses for GSR were carried out in three steps: the first step was map analysis for barium (Ba) to search for GSR particles from lead styphnate primed ammunition, or tin (Sn) to search for GSR particles from mercury fulminate primed ammunition. The second step was determination of the location of GSR particles by X-ray imaging of Ba or Sn at a magnification of x 1000-2000 in the SEM, using data of map analysis, and the third step was identification of GSR particles, using WDX spectrometers. Analysis of samples from each primer of a stub took about 3 h. Practical applications were shown for utility of this method.     

Unusual sources of Sn in GSR. An experimental study by SEM and IBA

Gunshot Residue (GSR) produced by the discharge of a firearm often provides very useful information in criminal investigations in cases involving the use of firearms. Scanning Electron Microscopy equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDS) is typically used worldwide to visualize micrometric particles constituting GSR and to analyse their elemental composition. The 2017 ASTM Standard guide for gunshot residue analysis by scanning electron microscopy/energy dispersive X-ray spectroscopy specifies that “Particles classified as characteristic of GSR will have one of the following elemental compositions: Lead, antimony, barium; Lead, barium, calcium, silicon, tin”. For the first time, the presence of an additional element, such as Sn, plays a key role in ASTM particle classification. It is known that some ammunitions, used for pistols, revolvers and rifles, contain tin foil discs for sealing the primer mixture into the cup, resulting in GSR particles containing Sn. The authors faced some cases in which Sn was unexpectedly found in GSR particles from a 0.22 Long Rifle derringer and from some 12 gauge shotguns. No tin foil discs are used in rimfire ammunitions and there is no published evidence of tin foil discs in shotshell ammunitions. Following a “case by case” approach, experimental research has been carried out to explain how Sn can be present in GSR particles when the last discharged cartridge also does not contain any Sn either in components and in the explosive charges.Moreover, the use of Particle Induced X-ray Emission (PIXE) showed the capability to overcome overlap ambiguity of Sb and Sn peaks in the X-ray spectra, being a possible key issue in real shooting cases if Sn quantities are below the lower limit of SEM detection, especially when Sb is also present.     

微波消解ICP/AES标准加入法测定尿液中金属毒物

目的建立微波消解ICP/AES标准加入法测定尿液中As、Ba、Pb、Cd、Cr、Zn、Sb金属毒物。方法取1.0mL尿样,加入3mL浓硝酸和0.5mL双氧水,进行微波消解。冷却后,用2%的硝酸定容至10.0mL。采用标准加入ICP/AES法进行定量分析,并优选实验条件及考察方法可靠性。结果尿液中As、Ba、Pb、Cd、Cr、Zn、Sb回收率在98.6%～104%之间;检出限在2.0～5.1ng/mL之间;线性范围Zn为5.0～200.0μg/mL,其余元素为0.5～20.0μg/mL。采用本文方法测定与国家标准物质人发和牛肝数据测定值基本一致。结论该方法回收率高、检测限低、能多元素同时测定,可以用于尿液中金属元素的检测。     

血中十六种挥发性碳氢化合物的固相微萃取

为认定火灾现场烧死尸体 ,用固相微萃取技术从血中快速提取十六种碳氢化合物 (直链烃从八碳到十三碳 ,芳香烃从二甲苯异构体到三甲基苯 )。在室温条件下直接用 10 0 μm 聚二甲基硅氧烷萃取头以顶空方式萃取浓缩2 0min。气相色谱仪 ,氢火焰检测器测定 ,外标法定量。结果显示 :血中检测浓度可达 0 1μg/ml。固相微萃取是筛选血中碳氢化合物一种灵敏而准确的方法。     

Detecting Gunshot Residue from Sellier & Bellot Nontox Heavy Metal‐free Primer by in situ Cathodoluminescence

Gunshot residue (GSR) from the discharge of ammunition can provide crucial information in reconstructing criminal cases. Traditional primers create particles of heavy metals such as lead, barium, and antimony. In forensic laboratories, automatic inorganic particle detection is performed by scanning electron microscopy (SEM), using the backscattered electron signal to search for bright residues among the many darker environmental particles, due to higher electron density of the former. Some innovative primers, indicated as heavy metal‐free (HMF), produce a residue of elements with atomic numbers below 21, urgently demanding new detecting solutions. For the first time, residues from Sellier & Bellot Nontox HMF primer are demonstrated to emit visible light under electron beam stimulation in a SEM. Cathodoluminescence is then proposed as a promising tool to both detect and characterize residues in forensic cases involving HMF primers, with minor changes to traditional analytical apparatus used for inorganic GSR analysis.