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Previous studies on the transference of gunshot residue (GSR) have shown that GSR can be transferred to surfaces through everyday activities and can persist on surfaces. Being that all police departments operate differently and have different spaces, GSR can be transferred and accumulates in different areas. Samples were collected from persons and surfaces in and around the Scranton Police Department and tested by scanning electron microscopy to identify GSR. Surfaces included police car seats, gun holsters, clothing around holsters, and belts around holsters. The results of the study showed that of the 25 samples collected, 40% contained at least one particle that was "characteristic of primer GSR", 64% contained at least one particle that was "consistent with primer GSR", and 92% contained at least one particle considered "commonly associated with primer GSR". This research characterizes where GSR is transferred within and around the police department. This data can be used to implement cleaning procedures or methods for decontamination. This study continues to strengthen the body of knowledge surrounding transferring of GSR. [ABSTRACT FROM AUTHOR]

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

3D-printing is an emerging technique that enables the fast prototyping of multiple-use devices. Herein we report the fabrication of a 3D-printed graphene/polylactic acid (G-PLA) conductive electrode that works as a sampler and a voltammetric sensor of metals in gunshot residue (GSR) using a commercially-available G/-PLA filament. The 3D-printed surface was used as swab to collect GSR and next submitted to a square-wave voltammetric scan for the simultaneous detection of Pb2+ and Sb3 + . The proposed sensor presented excellent analytical performance, with limit of detection values of 0.5 and 1.8 μg L−1 to Pb2+ and Sb3 + , respectively, and linear ranges between 50 and 1500 μg L−1. Sampling was performed through the direct contact of G-PLA electrode in hands and clothes of shooters, followed by immersion in the electrochemical cell in the presence of supporting electrolyte for the SWASV scan. The proposed method showed a great performance in the recovery, identification and semi-quantification of Pb2+ and Sb3 + in the evaluated samples without the need for sample preparation. Moreover, the device can be reused as sampler and sensor (until three times without loss of electrochemical performance) and the fabrication is reproducible (RSD = 7%, for three different devices). Hence, this 3D-printed material is an excellent candidate for the analysis of GSR, an indispensable analysis in the forensic field. Image 1 • 3D-printed graphene/PLA for the simultaneous determination of lead and antimony. • The same 3D-printed platform as a sampler and a voltammetric sensor of gunshot residues. • No need of surface modification with mercury/bismuth for highly sensitive detection. • Gunshot residues were analyzed by swabbing the 3D-printed electrode for further detection. • Free from interference of Cd, Cu, Fe, Hg and Zn and higher inter-electrode precision (7%). [ABSTRACT FROM AUTHOR]

Quantifying the strength of gunshot residue (GSR) evidence requires scientific knowledge about the number of particles expected to be found on individuals who were or were not involved in a shooting. However, controlled experiments demand expensive resources in terms of microscope time and labor, which restricts the data of most studies to only a small group of individuals. We suggest a novel method that exploits data collected routinely on suspects during the daily work of forensic laboratories. These observational data relate to both persons who were involved in a shooting and innocent individuals. We suggest a mixture approach with different models for the number of gunshot residue particles in each group and develop an iterative algorithm to estimate the probabilities of observing the evidence under the defense proposition that the suspect is innocent and under the prosecution assumption that he is not. The method is applied to data of more than 500 suspects collected by the Israel National Police Division of Identification and Forensic Science. The analysis shows that the probability of finding three or more GSR particles on the hands of innocent suspects is very small, less than 1.5 in 1000 cases. Our new method enables researchers to use data on real cases, possibly supplemented by experimental data, in order to estimate the probabilities of a given GSR finding under the defense and prosecution propositions. [ABSTRACT FROM AUTHOR]

Ammunition primers consisting of a mixture of lead styphnate, barium nitrate, and antimony (III) sulfide, upon deflagration, lead to the formation of inorganic gunshot residue (GSR). The cations, from their predeflagration form, undergo reduction reactions during burning to form the classic spheroidal, micron‐sized particles indicative of GSR. However, the rapidly changing pressure and temperature of the reaction zone implies that the reactions cannot go to completion. In this study, we use a conductivity detector to show that GSR produces an electrical pulse which corroborates the incomplete redox chemistry. We find that the shape of some GSR formed in an electric field also suggests its nonneutral character. Tantalizingly, the formation of GSR might be a result of Coulombic repulsion shattering the molten droplets in to smaller spheroids. Lastly, we suggest that deposition or transfer of GSR could be influenced by static electricity, an area which should be further studied. [ABSTRACT FROM AUTHOR]

The collection of gunshot residue on fabric can be an arduous task due to the microscopic size of particles (blind collection) and sheddability of some fabrics. The introduction of luminescent markers and consequent formation of luminescent gunshot residue (LGSR) can facilitate this analysis. In this study, different fabrics were analyzed in order to verify the persistence of the LGSR on them, the possibility of collecting and analyzing particles by video spectral comparator (VSC) and SEM/EDS. Also, different colored fabrics were used as targets in order to investigate influence of fabric color on LGSR visualization. Furthermore, the influence of the fabric type in the distribution of the LGSR deposited around the projectile´s hole entrance was evaluated. The fabric sheddability did not alter collection of the particles or analysis. It was possible to observe and collect LGSR on all tested fabrics, even after the fabric had been shaken, or in colored fabrics. [ABSTRACT FROM AUTHOR]

Raman spectroscopy is one of many tools available to verify the molecular composition of an analyte. Due to its non-destructive nature and its ability to accurately discern differences in closely related molecular structures, it has become invaluable in many fields, including its potential for forensic gunshot residue detection. Firearm-related fatalities in the United States continue to rise and many of them remain unsolved. This necessitates tools that are better equipped to aid in the investigation of firearm-related crimes, capable of high-throughput analysis yet remaining sensitive to give accurate and valuable information. The comparative downside of Raman spectroscopy to neighboring techniques like mass spectrometry and nuclear magnetic resonance is its lower sensitivity. Surface-enhanced Raman spectroscopy allows for the benefits of Raman spectroscopy alongside the added lower limit of detection with the simple application of nanoparticles, typically gold. Unfortunately, these benefits have seen little on-site application due to the difficulty of translating methods from conventional tabletop Raman spectrometers to point-and-shoot portable Raman spectrometers which have even lower sensitivities (higher limits of detection). Herein, we outline a versatile methodology for the detection of 6 organic gunshot residue components (diphenylamine (DPA), ethyl centralite (EC), 2,4-dinitrotoluene (2,4-DNT), 2-nitrodiphenylamine (2-nDPA), 4-nitrodiphenylamine (4-nDPA), and N-nitrosodiphenylamine (N-nDPA)) in liquid-phase that allows us to detect millimolar concentrations of these analytes. Furthermore, we report calculated vibrational assignments for these 6 analytes in solution, alongside detailed peak-by-peak analyses on a portable instrument. We showed signal enhancement and lower LODs through our data processing as well as a proof-of-concept SERS enhancement in a complex liquid-phase matrix, with an increased sensitivity of 700% when using SERS. [Display omitted] • Detailed vibrational spectra for 6 gunpowder residues using a portable Raman. • Computational vibrational analyses of 2- and 4-nitrodiphenylamine. • Homogenous detection methodology for organic gunshot residue analytes. • Improved detection limit with pre-processing using a portable Raman and SERS. [ABSTRACT FROM AUTHOR]

The analysis of gunshot residue (GSR) has played an integral role within the legal system in relation to shooting cases. With a characteristic elemental composition of lead, antimony, barium, and a typically discriminative spheroidal morphology, the presence and distribution of GSR can aid in firearm investigations. In this experiment, three shots of low velocity rim-fire ammunition were fired over polished silicon collection substrates placed at six intervals over a 100 cm range. The samples were analysed using a Field Emission Gun Scanning Electron Microscope (FEG-SEM) in conjunction with an X-flash Energy Dispersive X-ray (EDX) detector, allowing for GSR particle analyses of composition and structure at the sub-micron level. The results of this experiment indicate that although classic spheroidal particles are present consistently throughout the entire range of samples their sizes vary significantly, and at certain distances from the firearm particles with an irregular morphology were discerned, forming “impact-disrupted” GSR particles, henceforth colloquially referred to as “splats”. Upon further analysis, trends with regards to the formation of these splat particles were distinguished. An increase in splat frequency was observed starting at 10 cm from the firearm, with 147 mm−2 splat density, reaching a maximal flux at 40 cm (451 mm−2), followed by a gradual decrease to the maximum range sampled. Moreover, the structural morphology of the splats changes throughout the sampling range. At the distances closest to the firearm, molten-looking particles were formed, demonstrating the metallic residues were in a liquid state when their flight path was disrupted. However, at increased distances-primarily where the discharge plume was at maximum dispersion and moving away from the firearm, the residues have had time to cool in-fight resulting in semi-congealed and solid particles that subsequently disrupted upon impact, forming more structured as well as disaggregated splats. The relative compositions of the characteristic elements that are present in GSR also change in the different splat morphologies sampled, which may contribute to the particles' physical structures. Two distinct populations of splats were also observed: circular and elongated, which suggest the residues hit the substrate at different angles. The difference in the splat impact angle can be ascribed to the position of the residues within the firearm discharge plume; particles get caught up in the vortex that is created by the discharge gases behind the projectile as it leaves the barrel, thereby affecting their directionality and flight time. This reasoning could also justify the existence of both spheroidal and splat particles at certain distances. The novel sampling and analytical techniques used in this experiment have provided previously unknown information in relation to GSR structure and formation which could have greater implications to its current analysis amongst laboratories and law enforcement agencies worldwide.

The susceptibility for recreational shooters to transfer gunshot residue (GSR) to both the interior and exterior of a vehicle is investigated. A comprehensive sampling protocol was used to assess the most likely areas of GSR transfer from recreational shooter contact, such as the steering wheel and the area, the firearms were stored (the trunk). Up to 315 characteristic GSR, particles were found in several locations throughout the interior of a vehicle. As many as 876 characteristic particles were found throughout a single vehicle. The data indicate that vehicles frequently occupied by firearms users are a potential source for inadvertent transfer of GSR to persons unrelated to firearm activity. In criminal cases where vehicles have been used, such transfer processes for GSR need to be considered within the context of any case interpretation. The implications for subsequent contamination and transfer processes from such vehicles require further investigation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The detection and analysis of gunshot residues expelled during the discharge of the weapon play a potential role in criminal investigations. In this work, organic gunshot residues produced by using automatic rifle Kalashnikov caliber: 7.62×39mm and semi-automatic pistol Makarov caliber: 9×18mm were studied using Raman spectrometry. Samples of gunshot residues were collected from tissues placed on the targets at various distances in the range of 0-100cm. A distance of 20cm was chosen for organic particles collection. The comparison between the spectra of gunshot particles and those of nitrocellulose and stabilizers samples indicates that it is possible to use Raman spectroscopy for organic GSR analysis, which makes possible the distinction of calibers containing propellants with diphenylamine and those with ethyl centralite as stabilizers. Principal component analysis and support vector machine method applied to the Raman spectral data ranging from 1800 to 800cm-1 allow a differentiation between the two sets of spectra. [ABSTRACT FROM AUTHOR]

• Bayes thereom is a useful approach in highlighting the limitations of GSR evidence. • Research into the prevalence of GSR by the scientific community is limited. • Indicative particles of GSR are not in the main reported in England and Wales. • No significance can be attached to the finding of a low level (1–3 particles) of GSR. • Total transparency is needed when assessing the significance of GSR evidence. This paper details the review of the gunshot residue (GSR) evidence relating to a 2002 murder involving the discharge of a pistol where the Prosecution used the GSR findings together with voice identification evidence and obtained a conviction in the case of R v Dwaine George. Mr George was subsequently represented by Cardiff University Law School's Innocence Project who made representations to the Criminal Cases Review Commission (CCRC) based on issues relating to the GSR evidence. The CCRC commissioned their own expert review and based on these findings referred the conviction to the Court of Appeal stating that in their opinion the weight of the GSR evidence was not appropriately conveyed to the jury at the original Trial and there should have been a warning relating to the limited significance that could be attached to the evidence. The Court of Appeal concluded that had the jury been aware of the full extent of the potential alternative sources of GSR in the case and the limited number of particles found on a jacket related to Mr George then this would have affected the decision of the Trial jury. The appeal was allowed and the convictions were quashed. [ABSTRACT FROM AUTHOR]

The detection and interpretation of gunshot residue (GSR) can play an important role in the investigation of firearm related incidents. Recently, the potential of organic compounds to provide an additional means to discriminate between GSR and environmental particles, in particular in cases where lead-free ammunition is used, has been highlighted. This work describes a method for the extraction and detection of complementary organic and inorganic compounds from a single GSR sample, using a methodology that makes implementation in the current standard procedure feasible. GSR samples were collected from the shooter's hands following double and single discharges, using the traditional adhesive carbon aluminium stubs. Analysis of organic compounds was performed using solid-phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), followed by analysis of the traditional inorganic particles using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Detection of both categorised organic GSR compounds (e.g. ethyl centralite, diphenylamine and 2-nitrodiphenylamine) and characteristic inorganic GSR has been achieved. Given the fact that the detected organic GSR compounds are relevant with respect to the confirmation of GSR materials, this method has successfully demonstrated the ability to obtain a total chemical profile from a single GSR sample, which has the potential to increase the probative value of GSR evidence. [ABSTRACT FROM AUTHOR]

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Recent work in the forensic analysis of Gunshot residues (GSR) has suggested that the sub-surface or internal composition and morphology of these residues be explored. A particular area of interest is in heavy metal free, or non-toxic ammunition, which are becoming more frequently encountered in the marketplace. As the formulation of the primer compound changes the conditions of the firearm discharge, there is the possibility that different primer formulations may result in the formation of different GSR particles with distinct internal morphologies and compositions. To that end, the internal morphology and composition of GSR particles may provide additional information that could be useful in the investigation of firearms crime. This research investigated the internal morphology of GSR originating from a variety of different ammunition products. Both traditional three-component primed ammunition, and a selection of heavy metal free and non-toxic alternatives were considered. Particles were identified using SEM-EDS, before being cross-sectioned using a focussed ion beam (FIB) instrument. The FIB-sectioned particles were then re-acquired and mapped using SEM-EDS, to assess both internal morphology and composition. Particles observed in this study presented distinct morphological and compositional features at the sub-particle level that may provide an indication of the primer formulation from which they originated. That said, further investigation of a variety of samples should be undertaken to verify the consistency of these features, or any deviations that may be observed based on primer type. However, these results indicate that there may be promise in obtaining additional detail from sub-particle morphology and composition. [ABSTRACT FROM AUTHOR]

In order to have confidence in the integrity of a GSR test result, it is essential to understand the factors that may influence the presence of GSR particles on a person of interest's hands beyond the discharge of a firearm. One important consideration is the possibility that a person of interest (POI) may become contaminated with GSR through their interactions with firearms-carrying police officers during the process of apprehension or arrest. This situation has the potential to result in a false positive error, and potentially result in the mistaken inclusion of a POI in an investigation. Prior studies have indicated that receiving a firearm at the start of shift represents a significant contamination event, which may result in GSR persisting on the hands of police officers (Cook, 2016). Firearms-carrying police officers were sampled at various points throughout their shift to ascertain the extent of persistence of GSR on their hands, as a potential population that could then be transferred. A secondary transfer study was also conducted, with several 'mock arrest' scenarios used as a means of modelling the extent and dynamics of any secondary GSR transfer. When compared to the random population, it was found that police exhibit GSR contamination of their hands at a higher frequency. 7.9% of the officers sampled in this study returned at least one, 3-component particle characteristic of GSR. Further, 75% of the officers tested had at least one particle considered consistent with GSR present on their hands. However, the overall particle numbers were relatively low, with the average reported number of characteristic particles being less than five, and the greatest number reported being twelve. When considering the possibility of secondary transfer occurring during the process of arrest, it was further determined through secondary transfer experiments that the most probable transfer situation was fewer than 25% of the particles present on an officer's hands would be transferred to a POI as a result of a short 'mock arrest' contact. We conclude that although the possibility of GSR contamination through the process of arrest exists, and is worthy of consideration in the assessment of GSR evidence, it is not an overwhelming, or major concern. [ABSTRACT FROM AUTHOR]

Abstract In forensics, the identification of gunshot residues (GSR) is a crucial point in firearm crime investigations. However, there is a lack of analytical methodologies to characterize the residues produced by non-toxic ammunition (NTA). To overcome this drawback, researchers have proposed the introduction of luminescent and chemical markers into ammunition. Luminescent markers, besides overcoming problems of NTA analysis, aid to identify and collect GSR by direct visualization of luminescent residues under UV radiation. Furthermore, the development of new markers with unique compositions has opened new perspectives about encoding ammunition. In this work, we propose the use of eight co-doped lanthanide metal-organic frameworks (Ln-MOF) [Y 1−X Ln X (BTC)] (wherein BTC = trimesic acid) containing discrete concentration levels of Eu3+, Tb3+, Sm3+ and/or Yb3+ ions, as chemical barcodes for ammunition. To assess the method efficiency, we performed blind tests in which neither the shooters and the analyst had knowledge about the marker present in each cartridge that was fired. After shots, the residues were collected and analyzed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and video spectral comparator (VSC) to identify the marker used. As result, all of the markers were correctly identified. In addition, correlation between the residues collected at different locations (as hands, firearm and shooting area) was possible. Therefore, the encoding method proposed proved to be a powerful analytical tool for firearm crime investigations, providing a level of information that cannot be achieved with the current methodologies. Graphical abstract Unlabelled Image Highlights • Luminescent markers were added to non-toxic ammunition and provided an easy and reliable way to identify gunshot residues. • Encoding ammunition was achieved using different markers with unique compositions. • A set of eight co-doped lanthanide metal-organic frameworks was used as chemical barcodes for ammunition. • Blind tests were performed and correlation between the residues collected at different locations was possible. • All analyzes were performed using facilities compatible with forensic routine (SEM/EDS and video spectral comparator). [ABSTRACT FROM AUTHOR]

Despite continued improvements in gunshot residue (GSR) detection and analysis, there are still challenges in the interpretation of GSR evidence. The level and distribution of GSR present on an individual can be influenced by many factors, dependent upon the context of any given case. Due and diligent attention must therefore be placed upon fate and behaviour processes in relation to GSR when assessing and interpreting any case findings. The distribution of GSR upon the body of a recreational shooter was assessed. Samples were taken from 17 positions across a shooter's body immediately after the discharge of one round of ammunition. The shooting hand prevailed as the most GSR-contaminated area, with as many as 351 characteristic GSR particles identified. The face and supporting hand also exhibited high levels of GSR contamination. This level of contamination raises questions concerning the fate and behaviour of GSR particles within the general environment, specifically with regard to transfer processes. [ABSTRACT FROM AUTHOR]

Visualization of nitrite residues is essential in gunshot distance determination. Current protocols for the detection of nitrites include, among other tests, the Modified Griess Test (MGT). This method is limited as nitrite residues are unstable in the environment and limited to partially burned gunpowder. Previous research demonstrated the ability of alkaline hydrolysis to convert nitrates to nitrites, allowing visualization of unburned gunpowder particles using the MGT. This is referred to as Total Nitrite Pattern Visualization (TNV). TNV techniques were modified and a study conducted to streamline the procedure outlined in the literature to maximize the efficacy of the TNV in casework, while reducing the required time from 1 h to 5 min, and enhancing effectiveness on blood‐soiled samples. The TNV method was found to provide significant improvement in the ability to detect significant nitrite residues, without sacrificing efficiency, that would allow for the determination of the muzzle‐to‐target distance. [ABSTRACT FROM AUTHOR]

Electroanalysis of organic residues of the propellant stabiliser ethyl-centralite (1,3 diethyl-1,3 diphenyl urea, EC) generated from the discharge of a weapon or improvised explosive devices is examined. Comparative effects of an electrode modifier, nanoparticles of magnetite (Fe 3 O 4), on the sensor performance was of interest, with customised printed prototype development and analysis of organic firearm residue (OFAR) samples. Differential pulse voltammetry (DPV) calibration studies realised sensitivity of 6.37 × 10−2 μA∙μM−1 (over the concentration range 2.5–50 μM) at the magnetic nanoparticle modified electrode, representing a 1.65 fold signal increase relative to unmodified electrodes with limit of detection 4.39 µM. Inclusion of the OFAR co-existing diphenylamine (DPA) stabiliser realised signal discrimination and sensitivity of 7.49 × 10−2 and 5.49 × 10−2 μA∙μM −1 for DPA, and EC respectively, using DPV over the same range. The work culminated in the qualitative and quantitative analysis of propellant stabilisers in firearm residue acquired from a single base shotgun shell, with recovery from a target sample cloth, together with unburnt propellant, making promising first steps towards a customised screen-printed prototype for use by forensic professionals. Scanning electron microscopy/energy dispersive spectroscopy and atomic force microscopy were employed for particle confirmatory analysis. [Display omitted] • Forensic electroanalysis of propellant stabilisers • Magnetic nanoparticle modified electrodes for signal enhancement. • Electrochemical investigation into redox activity of ethyl centralite. • Firearm residue recovery studies using in house fabricated printed transducer prototype. [ABSTRACT FROM AUTHOR]

A high performance liquid chromatography tandem mass spectrometry/mass spectrometry (HPLC-MS/MS) protocol was developed for the determination of diphenylamine (DPA). Four productions of DPA were selected for qualitative assay and the peak area of the main product ion for quantitation. By means of separation using an Agilent Extend-C18 column (CA, USA) (150 mm × 4.6 mm, 5 μm) with methanol-water (90:10) as the mobile phase, DPA was detected by electrospray ionization (ESI) tandem mass spectrometry in positive mode. The linearity of the peak area versus concentration ranged 5-500 ng/mL, r 2 = 0.9978. The limit of detection (S/N =3) of this method was 0.3 ng/mL. This method is applicable for the determination of DPA in gunshot residue.

The ability to manage, distil and disseminate the significant amount of information that is available from published literature is fast becoming a core and critical skill across all research domains, including that of forensic science. In this study, a simplified scientometric approach has been applied to available literature on gunshot residue (GSR) as a test evidence type aiming to evaluate publication trends and explore the interconnectivity between authors. A total of 731 publications were retrieved using the search engine ‘Scopus’ and come from 1589 known authors, of whom 401 contributed to more than one research output on this subject. Out of the total number of publications, only 35 (4.8%) were found to be Open Access (OA). The Compound Annual Growth Rate (CAGR) for years 2006 and 2016 reveals a much higher growth in publications relating to GSR (8.0%) than the benchmark annual growth rate of 3.9%. The distribution of a broad spectrum of keywords generated from the publications confirms a historical trend, in particular regarding the use of analytical techniques, in the study of gunshot residue. The results inform how relevant information extracted from a bibliometric search can be used to explore, analyse and define new research areas.

The paper discusses the examination of patterns of gunshot residue deposition on targets after cartridges loaded with Polev slugs are fired from a 12 gauge smoothbore shotgun. We have established that firing shotgun shells loaded with Polev slugs from a distance further than close range causes penetration of target material with smaller and larger lead particles within a 100 mm radius around the entrance hole. When shots are fired from a distance of 5-to-25 m, the radius of GSR deposition, the number and size of lead particles increase.

Our research group previously reported a novel method for the detection of gunshot residue (GSR) via tape lifting combined with Raman microspectroscopic mapping and multivariate analysis. This initial study achieved proof of concept for this approach. Here, we report validation studies which investigate the reproducibility/ruggedness and specificity of the approach. Raman mapping for GSR detection on adhesive tape was performed on an independent Raman microscope, not used to generate the training set. These independent spectra were classified against the original training dataset using support vector machine discriminant analysis (SVM-DA). The resulting classification rates of 100% illustrate the reproducibility of the technique, its independence upon a specific instrument and provide an external validation for the approach. Additionally, the same procedure for GSR collection (tape lifting) was performed to collect samples from environmental sources, which could potentially provide false-positive assignments for current GSR analysis techniques. Thus, particles associated with automotive mechanics were collected. Automotive brake and tire materials are often composed of the heavy metals lead, barium, and antimony, which are the key elements targeted by current GSR detection technique. It was determined that Raman spectroscopic analysis was not susceptible to misclassifications from these samples. Results from these validation experiments illustrate the great potential of Raman microspectroscopic mapping used with tape lifting as a viable complimentary tool to current methodologies for GSR detection. Furthermore, current methodologies are not well-developed for automated organic GSR detection. Illustrated here, Raman microscoptrosocpic mapping has the potential for the automatic identification of organic GSR.ᅟ [ABSTRACT FROM AUTHOR]

This paper reports on the development of low cost luminescent markers for gunshot residue (GSR) identification by a new room temperature precipitation synthesis route. These markers are metal-organic frameworks (MOFs) formed by the ligand 1,4-H 2 BDC (teraphthalic acid) and the metals Zn 2+ , Eu 3+ and Tb 3+ . The MOFs were synthesized by precipitation, using different ratios of zinc and lanthanides (1–100%). The synthesized MOFs were added to 9 mm NTA gunpowder and, after shots were fired, luminescent residues (LGSR) were visualized under UV radiation. The residues were collected and characterized by non-destructive techniques such as SEM-EDS and emission spectroscopy. All MOFs presented high luminescence. However, those with levels of Eu 3+ above 10% or Tb 3+ above 5% presented the best cost-benefit. Comparing with the marker containing only lanthanide ions, this represents a cost reduction of up to 7-times. Besides, the precipitation synthesis represents an innovation in developing crystalline, high luminescent and stable luminescent markers for GSR identification. [ABSTRACT FROM AUTHOR]

The realm of forensics is scientifically complex with multiple disciplines utilizing a plethora of analytical techniques to identify, detect, and differentiate between countless types of evidence for solving crimes. The rapid, highly-selective, and nondestructive method of Raman spectroscopy (RS) has shown continued promise for analysis of many types of forensic samples. The incorporation of chemometrics further enhances the specificity of RS, and offers the opportunity of automatic data analysis and estimation of error rates, which are important requirements for modern forensic tools. Applications of RS in forensic serology and for the analysis of gunshot residue (GSR) were chosen for this review since RS promises significant advancement of these areas for practical forensics. The studies included here, particularly with the utilization of portable instrumentation, support how crucial RS is to the field of forensic science, and should help facilitate its incorporation for routine sample analysis in the near future. [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]

Abstract: Powder stippling caused by the impact of propellant particles during close‐distance gunfire has been previously described on skin and solid objects only. Additionally, radial tearing has been described as clear evidence of a contact‐distance shot, requiring no further testing. Patterns of discrete perforating holes (referred to here as “stippling perforations”) and other physical damage on sweatshirt fleece fabrics were prepared. Using the firearm and ammunition in this study, stippling perforations were observed to a maximum muzzle‐to‐target distance of 35 cm (10 inches). In addition, radial tearing and disintegration were present (and often more extensive) at greater than contact distance. The presence of stippling perforations could augment muzzle‐to‐target distance estimates generated using the Griess test, or allow distance estimates when the Griess test is not feasible. Unlike what has been previously reported, testing on the original evidence (or similar substitute) is warranted when physical damage is used to estimate shooting distance. [ABSTRACT FROM AUTHOR]

A review of the literature concerning the fate and behavior of gunshot residue ( GSR) is presented. A number of concomitant parameters including firearm and ammunition type, plume and GSR material characteristics, travel distances, chemical composition and GSR morphology are critically discussed in relation to their effects on the distribution and deposition, transfer and persistence processes of GSR. The underlying mechanisms associated with such processes are also considered. Knowledge of these processes on GSR materials could provide valuable information concerning scene preservation and subsequent forensic sampling. The number of GSR particles deposited can vary significantly with each firearm discharge, highlighting the potential to produce distinctive data in each individual case. With the continual development and compositional changes of new ammunition types, further evaluation of the effect these processes may have on GSR evidence and their possible influence on the interpretation of the analytical results should be given due consideration. [ABSTRACT FROM AUTHOR]

This report outlines a case in which cranial gunshot trauma was suspected, but a large portion of the cranium was not recovered from the scene, so the precise nature and etiology of the fractures could not be determined with certainty. Scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (SEM-EDS) is widely accepted as a reliable method for detecting gunshot residue (GSR) on the hands of shooters and on fleshed remains, and experimental research has shown that the technique is applicable to skeletal remains. Therefore, SEM-EDS was utilized to analyze several cranial fragments and a control fragment from a thoracic vertebra for gunshot residue. The technique enables the examination of particle morphology and elemental composition of the inorganic compound. Barium, antimony, and lead were detected on four of the five cranial fragments, confirming the presence of gunshot residue. The fifth fragment had barium and lead, but no antimony. No trace elements were detected on the control fragment from the thoracic vertebra. SEM analysis of the bone surface revealed the presence of characteristic GSR spherical deposits on three of the fragments. The combined presence of signature trace elements and spherical surface deposits on the cranial fragments are consistent with the presence of gunshot residue. The cause of death was certified as disruptive head trauma, and given the circumstances of the case the manner of death was certified as homicide. The SEM-EDS analysis confirmed and supported the pathologist's and anthropologist's assessment of the circumstances surrounding the death. [ABSTRACT FROM AUTHOR]

Gunshot residues (GSR) are important physical evidence in firearm-related crimes. Recently developed non-toxic ammunition, however, requires a new methodology for its characterization. To overcome this drawback, the introduction of noncommercial luminescent markers in ammunition was proposed. These markers, synthesized and added to the gunpowder, presented as a versatile tool for GSR analysis, since they require UV radiation alone to visualize the luminescent GSR (LGSR). This has opened up new perspectives for understanding GSR behavior at a crime scene. This work aims to expand previous studies performed with the luminescent markers in forensic contexts, exploring four different important aspects related to GSR behavior. Using LGSR amount/dispersion and a series of blind tests with marked ammunition, we tried to (1) identify the shooter position; (2) estimate the shooting distance; (3) evaluate the influence of the pistol type on the LGSR distribution on the shooter's hands and guns; and (4) study the transference of LGSR by a chain of handshaking. For this purpose, a portable UV lamp (λ=254nm) and/or techniques such as video spectral comparator (VSC) and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS) were used to visualize and analyze the residues. As a result, the observation of the LGSR enabled accurate determination of the shooter position and the firing distance without any chemicals. Besides, the LGSR were visualized on different kinds of pistols, regardless of firing mechanism. And finally, this study evidenced transference of residues from shaking hands with the shooter, which should be carefully considered when interpreting the results of a GSR analysis. [ABSTRACT FROM AUTHOR]

Detection and identification of organic and inorganic components of gunshot residue are well established within forensic chemistry because of highly characteristic and uncommon features of the products of ammunition discharge at the time and place of a shooting incident in comparison to other materials present in daily life of people. Both types of residue play an important role in establishing various circumstances of a shooting crime, though the most vital one concerns the possibility of relating a suspect with the activity of shooting. In this aspect, solid, inorganic particles, nowadays called characteristic, have been utilized. Their specific features result from the primer mixture composition, including compounds of heavy metals, lead, antimony, and barium, and from the extraordinarily dynamic conditions of their formation, taking place at the moment of the primer detonation. Scanning electron microscopy and X-ray microanalysis techniques proved to be necessary and sufficient to reveal the content and the spherical morphology of the particles for this purpose. Recently, the recommendation that the potential for lead exposure be minimized was followed in the production of ammunition cal. 9 mm Luger, 0.40 S&W, 0.380 Auto, and 0.38 Special. These modern types of ammunition expel less characteristic particles, the identification of which can be a challenge for the examiners. At least two solutions to strengthen the residue identity are taken into account: additional insights into the internal structure of inorganic particles, e.g., by means of electron backscattered diffraction and focused ion beam, as well as complementary examinations of organic residues with sensitive mass spectrometric techniques. [ABSTRACT FROM AUTHOR]

In the course of providing assistance to legal counsel in a matter that involved the analysis of firearms propellant by gas chromatography/mass spectrometry it was noticed that phenoxazine was reported as a component of 0.22 calibre propellant that contained diphenylamine as the stabiliser. The research was conducted to find how phenoxazine was formed. The results showed that the compound was not phenoxazine but a diphenylamine derivative 4-(phenylimino) cyclohexa-2,5-dien-1-one that formed in the injection port of the gas chromatograph. In addition a second artefact was found to form in the ion source of the mass spectrometer. While the presence of the artefacts does not affect the ability to identify particles as propellant they may impact on comparison with source ammunition. [ABSTRACT FROM AUTHOR]

Infrared photography is interesting for a use in forensic science and forensic medicine since it reveals findings that normally are almost invisible to the human eye. Originally, infrared photography has been made possible by the placement of an infrared light transmission filter screwed in front of the camera objective lens. However, this set-up is associated with many drawbacks such as the loss of the autofocus function, the need of an external infrared source, and long exposure times which make the use of a tripod necessary. These limitations prevented up to now the routine application of infrared photography in forensics. In this study the use of a professional modification inside the digital camera body was evaluated regarding camera handling and image quality. This permanent modification consisted of the replacement of the in-built infrared blocking filter by an infrared transmission filter of 700nm and 830nm, respectively. The application of this camera set-up for the photo-documentation of forensically relevant post-mortem findings was investigated in examples of trace evidence such as gunshot residues on the skin, in external findings, e.g. hematomas, as well as in an exemplary internal finding, i.e., Wischnewski spots in a putrefied stomach. The application of scattered light created by indirect flashlight yielded a more uniform illumination of the object, and the use of the 700nm filter resulted in better pictures than the 830nm filter. Compared to pictures taken under visible light, infrared photographs generally yielded better contrast. This allowed for discerning more details and revealed findings which were not visible otherwise, such as imprints on a fabric and tattoos in mummified skin. The permanent modification of a digital camera by building in a 700nm infrared transmission filter resulted in a user-friendly and efficient set-up which qualified for the use in daily forensic routine. Main advantages were a clear picture in the viewfinder, an auto-focus usable over the whole range of infrared light, and the possibility of using short shutter speeds which allows taking infrared pictures free-hand. The proposed set-up with a modification of the camera allows a user-friendly application of infrared photography in post-mortem settings. [ABSTRACT FROM AUTHOR]

Research into the deposition patterns of primer gunshot residue ( GSR) beyond a primary target was previously nonexistent. This study aimed to determine the deposition patterns of GSR once a bullet passed through an initial target and continued on its path into additional targets. Multiple repetitions were performed to assess the GSR deposition patterns after a bullet was shot through a closed window into either a dummy or a wall within an enclosed room. Samples were taken from both the primary and secondary target holes as well as from nontarget areas. Significant amounts of GSR were found on all samples. The results show that GSR continues to be deposited along the path of the bullet after passing through a primary glass target. These findings reiterate the lack of probative value in collecting GSR samples from gunshot victims even if they are in an enclosed area separate from the shooter. [ABSTRACT FROM AUTHOR]

In this article a 2-levelmultinomialmodel for the calculation of Likelihood Ratios (LRs) as ameasure of the strength of evidence in the case of categorical evidence is introduced. In order to illustrate its usage, it is applied to gunshot residue (GSR) comparison data obtained in an experimental set-up and analysed using electron microscopy. The data consists of a number of gunshot residues divided in k categories depending on their elemental composition. For comparison a score-based model (the Pearson correlation) and a 1-levelmultinomial model estimated with MaximumLikelihood (ML)were also applied on the same data. Three variations of the 2-level multinomial model were tested, together with the other twomodels. The results show that all testedmodels can be applied on categorical data such as GSR. The 2-level multinomial model, the model that is introduced in the study, shows the least misleading evidence. Furthermore this article demonstrates a first step taken towards a system that calculates numerical LRs in GSR comparison studies. [ABSTRACT FROM AUTHOR]

The defendant, the driver of the questioned car, allegedly extended his right arm over the passenger seat and fired a single shot from a 380 pistol out the passenger window with the pistol's breech within the car. A simulation of this shooting scenario using the same model car, but different year, was conducted to quantitate gunshot residue (GSR) contamination of interior surfaces within the car. The test car's dash and headliner/window frame above the pistol had the heaviest GSR contamination. The dash GSR from airborne deposition documents a firearm discharge within the vehicle. Transfer from GSR-contaminated hands or clothing to the dash is unlikely. The heavy GSR contamination of the headliner/window frame above the pistol likely documents the window from which the pistol was fired, but additional experiments are needed to verify. [ABSTRACT FROM AUTHOR]

This study investigated the use of laser-induced breakdown spectroscopy (LIBS) and scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX) as means of characterizing gunshot residue (GSR) originating from commercially available lead-free rounds. Data from two experiments are presented in this work. One experiment focused on identifying prominent analytical markers present in lead-free GSR by LIBS while the other applied SEM-EDX to determine the degree of evidence preservation after LIBS analysis. Samples of GSR were collected via tape-lift method from the hands of volunteer shooters and instrumental analyses were conducted in triplicate. As a result, the lead-free ammunition analyzed in this work generated GSRs comprising primarily Ba, Al, Si, and/or K. Trace amounts of Ti, Fe, and S were also apparent in some compositions. Through SEM-EDX analysis, a spheroidal geometry consistent with traditional lead-containing GSR was observed. Additionally, it was determined that evidence is preserved after LIBS analysis which supports the implementation of LIBS as a rapid preliminary screening method followed by confirmatory testing via SEM-EDX on the preserved evidence. [ABSTRACT FROM AUTHOR]

Simultaneous determination of nitrate and nitrite in gunshot residue has been conducted by capillary electrophoresis using an acidic run buffer ( pH 3.5). In previously developed capillary electrophoretic methods, alkaline pH separation buffers were used where nitrite and nitrate possess similar electrophoretic mobility. In this study, the electroosmotic flow has been reversed by using low pH running buffer without any additives. As a result of reversing the electroosmotic flow, very fast analysis has been actualized, well-defined and separated ion peaks emerge in less than 4 min. Besides, the limit of detection was improved by employing large volume sample stacking. Limit of detection values were 6.7 and 4.3 μM for nitrate and nitrite, respectively. In traditional procedure, mechanical agitation is employed for extraction, while in this work the extraction efficiency of ultrasound mixing for 30 min was found sufficient. The proposed method was successfully applied to authentic gunshot residue samples. [ABSTRACT FROM AUTHOR]