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• Inorganic GSR from PPU ammunition cal. 7.65 mm were studied. • GSR patterns on cotton fabric in the range 25–125 cm are presented. • Distribution of GSR was established by SEM-EDX analysis. • Chemical and morphological GSR spread dependence on the shooting distance is demonstrated. • Empirical bases for forensic casework on shooting to assist casework were achieved. The subject of this research was the inorganic gunshot residue component collected from shooting patterns obtained on woven cotton cloth using a Pietro Beretta model 70 pistol, cal. 7.65 mm and Serbian ammunition for the following muzzle-to-target distances: 25, 50, 75, 100 and 125 cm. For each distance, three rounds of shooting were performed. Particles were lifted within a 10 cm radius of the projectile entrance and automatically analyzed using a scanning electron microscope coupled with an energy dispersion X-ray spectrometry. The obtained data on the populations of particles were analyzed taking into account their numbers, chemical classes and sizes. The results showed an apparent maximum incidence within all particles containing barium at about 50 cm distance. Also, lead particles revealed a distinct behaviour, being dominant at a 25 cm distance, falling below the other chemical classes, and finally becoming dominant again at 125 cm. The analysis of the frequency of occurrence of particles sorted according to their sizes confirmed that the small particle population is the largest, and their distribution in function of the equivalent circle diameter is exponential-like. The obtained results provided knowledge on the distribution of particles in the vicinity of the tested firearm and ammunition cal. 7.65 mm which generally corroborates with similarly studied GSR distributions obtained for the use of pistols cal. 9 mm. This information, together with the examinations of gunshot damages and other types of residues such as soot or unburned propellant grains may support qualitative inferences on shooting distance estimation, especially in cases, when the firearm and cartridges are not available to perform test shooting. In such cases even roughly estimated shooting distance can be helpful, e.g. for confirming or excluding the possibility of self-inflicted injuries or suicide and infer on the mutual position of the shooting stage actors. An example of casework that illustrates intermediate shooting distance estimation is presented. [ABSTRACT FROM AUTHOR]

Due to their portability, sensitivity, and ease of use, electrochemical sensors have recently become a popular method for rapid, on-site analysis. This study presents a proof of principle for the application of modified screen-printed carbon electrodes (SPCEs) for the detection of signature metals (Pb, Sb, and Zn) commonly found in gunshot residue (GSR), as well as for the detection of nitrate/nitrite in organic GSR and low explosives. To achieve these two aims, we have examined various electrode surface modifications. For metal detection, SPCEs were modified by electrodeposition of gold to improve sensitivity. GSR samples taken from two types of cartridge cases and shooting-related surfaces were analyzed using the Au-modified SPCEs. For nitrate/nitrite analysis, further electrode surface modifications were carried out by depositing Cu(II) onto the Au-SPCEs to enhance signal through catalytic activity of the copper surfaces. Both unburned and burned forms of black powder samples, as well as burned smokeless powder, were then analyzed using the Cu/Au-SPCEs. In conclusion, due to their low cost and portability, these sensors should prove useful for rapid forensic examination. [Display omitted] • Screen-printed carbon electrodes modified with gold and copper for GSR/explosives. • Stripping voltammetry detects Pb(II), Sb(III), and Zn(II) in GSR from cartridges. • Modified electrodes allow simultaneous NO 3 - and NO 2 - detection in GSR/explosives. • Results show proof-of-principle for GSR/explosives detection in a limited sample set. [ABSTRACT FROM AUTHOR]

The evaluation of criminal cases involving the discharge of a firearm requires reliable and up to date information regarding the transfer and persistence of gunshot residue (GSR). Similarly, knowledge of background levels of GSR on relevant populations and awareness of the potential for contamination/secondary transfer is essential. In this paper we build on previous work published by this laboratory and provide an update on the frequency of gunshot residue types in discharged cartridge casings (DCC) encountered in casework within the Republic of Ireland. In conjunction, an examination of the types of firearms encountered in casework and the associated residue types is undertaken. Finally, a review of levels of GSR particles detected on control samples taken from members of An Garda Síochána, the Irish police is detailed. Control samples are taken before a police officer samples a detainee suspected of involvement in an incident where a firearm was discharged and/or subsequently handled. • Examination of discharged cartridge casings encountered in case work. • Frequency of gunshot residue types encountered in case work. • Control samples taken from the hands of police officers before sampling of suspects. • Background levels of gunshot residue encountered on control samples. • Evaluation of gunshot residue findings. [ABSTRACT FROM AUTHOR]

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]

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 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]

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]

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]

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]

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]

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]

Estimating the time since discharge of spent cartridges can be a valuable tool in the forensic investigation of firearm-related crimes. To reach this aim, it was previously proposed that the decrease of volatile organic compounds released during discharge is monitored over time using non-destructive headspace extraction techniques. While promising results were obtained for large-calibre cartridges (e.g., shotgun shells), handgun calibres yielded unsatisfying results. In addition to the natural complexity of the specimen itself, these can also be attributed to some selective choices in the methods development. Thus, the present series of papers aimed to systematically evaluate the potential of headspace analysis to estimate the time since discharge of cartridges through the use of more comprehensive analytical and interpretative techniques. Following the comprehensive optimisation and validation of an exhaustive headspace sorptive extraction (HSSE) method in the first part of this work, the present paper addresses the application of chemometric tools in order to systematically evaluate the potential of applying headspace analysis to estimate the time since discharge of 9mm Geco cartridges. Several multivariate regression and pre-treatment methods were tested and compared to univariate models based on non-linear regression. Random forests (RF) and partial least squares (PLS) proceeded by pairwise log-ratios normalisation (PLR) showed the best results, and allowed to estimate time since discharge up to 48h of ageing and to differentiate recently fired from older cartridges (e.g., less than 5h compared to more than 1-2 days). The proposed multivariate approaches showed significant improvement compared to univariate models. The effects of storage conditions were also tested and results demonstrated that temperature, humidity and cartridge position should be taken into account when estimating the time since discharge. [ABSTRACT FROM AUTHOR]

Estimating the time since discharge of spent cartridges can be a valuable tool in the forensic investigation of firearm-related crimes. To reach this aim, it was previously proposed that the decrease of volatile organic compounds released during discharge is monitored over time using non-destructive headspace extraction techniques. While promising results were obtained for large-calibre cartridges (e.g., shotgun shells), handgun calibres yielded unsatisfying results. In addition to the natural complexity of the specimen itself, these can also be attributed to some selective choices in the methods development. Thus, the present series of paper aimed to more systematically evaluate the potential of headspace analysis to estimate the time since discharge of cartridges through the use of more comprehensive analytical and interpretative techniques. Specifically, in this first part, a method based on headspace sorptive extraction (HSSE) was comprehensively optimised and validated, as the latter recently proved to be a more efficient alternative than previous approaches. For this purpose, 29 volatile organic compounds were preliminary selected on the basis of previous works. A multivariate statistical approach based on design of experiments (DOE) was used to optimise variables potentially involved in interaction effects. Introduction of deuterated analogues in sampling vials was also investigated as strategy to account for analytical variations. Analysis was carried out by selected ion mode, gas chromatography coupled to mass spectrometry (GC-MS). Results showed good chromatographic resolution as well as detection limits and peak area repeatability. Application to 9mm spent cartridges confirmed that the use of co-extracted internal standards allowed for improved reproducibility of the measured signals. The validated method will be applied in the second part of this work to estimate the time since discharge of 9mm spent cartridges using multivariate models. [ABSTRACT FROM AUTHOR]

Previous research has raised the possibility that automotive brake pads can produce particles that are both compositionally and morphologically similar to gunshot residue (GSR). These studies, published in the early 2000s, coincided with the reduction or removal of unnecessary sources of lead from the automotive industry. The question therefore arises whether modern brake pads might still be a relevant source of 'GSR-like' particles. In the present study, a total of 75 brake pads taken from a range of cars currently on the road in Adelaide, South Australia, were collected from service centres. These pads were screened by XRF, and 12 were selected as representatives of the types of pads available on the market. Some pads generated XRF results for elements particularly relevant to GSR analysis. Signals for barium and antimony were commonly observed, with some pads showing results possibly attributable to lead. The surfaces of these 12 pads were directly sampled using aluminium stubs equipped with carbon-filled adhesive tape. Following this, they were screened using SEM-EDS and an automated GSR particle search in order to detect particles containing lead, barium or antimony. No particles containing all of these elements were found, although a large number of particles containing both barium and antimony were located. Other particulate samples were collected using stubs from persons or objects associated with brakes in order to examine whether particles similar to GSR might be present on them. No three-component particles were detected in samples collected from the wheel rims or the hands of those exposed to automobiles. From this study of common, contemporary cars, brake pads and brake pad technicians, it was determined that the possibility of obtaining three-component 'GSR-like' particles from brake pads appears to be much lower now than when this issue was first raised in the early 2000s. While some brake pads do produce particles containing barium and antimony, they are often angular particles that contain sulphur. Furthermore, these 'GSR-like' particles are commonly found together with an abundance of particles containing iron. The particle evidence evaluated in total allows clear differentiation between residues originating from brakes and residues originating from firearms. [ABSTRACT FROM AUTHOR]

This study reports the synthesis of two new Eu3+ β-diketonates and their complete experimental and theoretical spectroscopic characterizations. These compounds present [Eu(tta) 3 (ε-cap)(H 2 O)] 1 and [Eu(btfa) 3 (ε-cap)(H 2 O)] 2 , supported by 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta), 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbtfa) formulas with a ε-caprolactam molecule acting as an ancillary ligand. These ligands act as efficient sensitizers for the Eu3+ ion, giving rise to an intense red emission. Due to this intense luminescence, compounds [Eu(tta) 3 (e-cap)(H 2 O)] 1 and [Eu(btfa) 3 (e-cap)(H 2 O)] 2 were selected as markers for the ammunition of a 38-caliber revolver and 0.380 pistol, respectively. This application is unprecedented for Eu3+ β-diketonates. The forensic assays indicated evident formation of luminescent gunshot residues (LGSR). Thus, these compounds may play an efficient role as allies in elucidating crimes. Luminescent Eu3+ β-diketonates as gunshot residue markers. [Display omitted] • In this work, two new luminescent Eu3+β-diketonates are presented. • The T 1.→ 5D 1 and T 1 → 5D 0 are the main channels responsible for luminescence. • The compounds were selected as markers in firearms ammunition. • The forensic tests showed which these compounds can support public safety. [ABSTRACT FROM AUTHOR]

If police officers are contaminated with gunshot residue (GSR) through the normal receiving, checking, loading, and securing of their issued firearm, there is the potential for secondary transfer of GSR to anyone those officers arrest during their shift. This 3-part study examined the level of GSR contamination of police officers following the start-of-shift handling of their standard issue firearm, the impact that hand-washing or the use of a self-drying hand-wash had on the level of GSR contamination, and the likelihood of officers re-contaminating their hands through contact with the exposed hand-grip of their holstered hand-gun. Almost 85% (28/33) of officers sampled had 3-component GSR particles on their hands immediately following the start-of-shift handling of their firearm. There was an average of 64 such particles over the 33 officers sampled. Of the 17 officers who washed their hands after securing their firearm, a single 3-component particle was recovered from the hands of one officer. GSR particles (maximum of 4) were recovered from 3 of the 14 officers who used self-drying hand gel following firearm handling. 3-component particles (maximum of 7) were recovered from the hand-grips of 12 of the 34 unissued handguns sampled. [ABSTRACT FROM AUTHOR]

For the first time, a classification system for organic gunshot residue (OGSR) compounds with respect to the confirmation of OGSR materials is presented. There are 136 compounds considered to be associated with OGSR that have been highlighted in the literature. Many of these compounds could be classified as being ubiquitous in the environment and thus their detection as characteristic components of OGSR could cause issues with the interpretation of chemical ballistic evidence. The proposed system aims to address this problem by classifying OGSR compounds based on their forensic relevance with respect to the confirmation of GSR materials. To increase the forensic relevance of such a system, the large number of OGSR compounds reported in the literature has been decreased to 20 OGSR compounds based on the organic chemical composition of over 200 propellant powders. Occupational and environmental materials also associated with OGSR compounds have been considered. [ABSTRACT FROM AUTHOR]

Gunshot residue (GSR) is a valuable form of forensic trace evidence in the investigation of firearms-related suicide and crime. In order to ensure that such evidence is given appropriate evidential weighting when it comes to case investigations, the dynamics of the deposition and distribution of GSR must be understood. As the activity of the subject after firing is a major factor in the retention of GSR, cases of suicide involving a firearm provide an opportunity to assess GSR distribution where post-shooting activity is not an issue, assuming the subject had not been moved. Seventy-one cases of suicide by gunshot in South Australia between 1998 and 2014 were examined to collect data on firearm type, calibre, and gunshot residue test results. Overall, 47% of cases were found to produce GSR results that were not of high probative value, even though it was known that the shooter had fired a firearm. Of particular interest were cases involving 0.22 rimfire ammunition, for which characteristic particles are not expected due to lack of antimony present in the primer. Despite this, 64% of these cases resulted in the detection of antimony-containing, three-component particles. [ABSTRACT FROM AUTHOR]

When considering the impact and value of gunshot residues (GSR) as forensic trace evidence, the likelihood of a suspect producing a positive GSR analysis result without having direct exposure to a firearm is a major consideration. Therefore, the random prevalence of GSR and 'GSR-like' residues in the wider population is a highly pertinent question when considering the probative value of such evidence. The random prevalence of GSR in two Australian jurisdictions - Victoria and South Australia - was assessed through the collection and analysis of GSR samples obtained from randomly selected members of the public. Volunteers were asked to declare any firearms use, hobbies or potential firearms exposure before allowing their hands to be sampled using aluminium GSR sample stubs coated in adhesive tape. A total of 289 samples, 120 from Victoria and 169 from South Australia were collected and analysed using scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDS). Across all samples, three 'characteristic' three-component Pb/Ba/Sb particles were detected from a single subject in South Australia, corresponding to an overall prevalence of 0.3%. Two-component 'consistent' particles were more prevalent, with Pb/Sb particles being the most frequently occurring, in 8% of samples, and in South Australia only. A number of samples, approximately 7%, showed populations of single element particles of Pb, Ba and Sb, which has the potential to generate a false positive for GSR if using a bulk analysis technique such as NAA or AAS. The prevalence of GSR or 'GSR like' particles in this study matches closely with similar surveys conducted in other jurisdictions. Such surveys are a useful foundation for the creation of a probabilistic method for the assessment of GSR evidence. [ABSTRACT FROM AUTHOR]

The 2D metal-organic framework (MOF) [Dy(DPA)(HDPA)] (where H 2 DPA=dipicolinic acid) was synthesized under hydrothermal conditions and exhibited a whitish yellow color (CIE coordinates: 0.362, 0.416) when excited at 365 nm. This color arises from the simultaneous blue ( 4 F 9/2 – 6 H 15/2 ), yellow ( 4 F 9/2 – 6 H 13/2 ) and red ( 4 F 9/2 – 6 H 11/2 ) transitions of Dy 3+ . This MOF exhibited a high potential for use as a luminescent marker for gunshot residue (GSR) and in the ammunition encoding process because it was possible to observe visually the luminescent gunshot residue (LGSR) on the shooter’s hands, both on the firearm and at the firing range, using an UV lamp. These particles were easily collected and characterized by photoluminescence spectroscopy and SEM–EDS. The particles exhibited a typical morphology and a composition, making them easy to differentiate from particles of occupational or environmental origin. [ABSTRACT FROM AUTHOR]

A comprehensive review of the literature concerning all aspects of sampling and analytical techniques used for the determination of organic gunshot residue (OGSR) compounds is presented. Currently, 136 compounds associated with OGSR have been identified in the literature. Despite this area gaining increasing attention and recognition in recent years, there is still an absence of a set combination of sample collection, extraction and analysis methods that are universally optimal for the treatment of any given OGSR sample. Moreover, there are no generally accepted guidelines for selecting the compounds of interest that will inform sampling and analysis protocols. We highlight recent developments in both extraction and analytical methods employed for their detection. The main advantages and disadvantages of the sampling and analysis methods are critically discussed. [ABSTRACT FROM AUTHOR]

Spherical particles produced by firearms loaded with a traditional ammunition reveal characteristic elemental contents and so their identification may provide a significant evidence in criminal investigations. With the advent of modern technologies in manufacturing ammunition, which replace toxic compounds of lead, antimony and barium in the primer mixture by elements and compounds such as powdered aluminium, titanium, amorphous boron or calcium silicide, differentiation between gunshot residue and morphologically similar particles originating from other anthropogenic or natural sources becomes more difficult. This work provides a chemical and morphological characterisation of welding fume particles originating from both the core and the covering of electrodes used in popular manners of welding steel and aluminium alloy constructions. With the use of scanning electron microscopy and energy dispersive X-ray spectrometry it has been established that single spherules containing aluminium, titanium or a set of such elements as aluminium, silicon, potassium and calcium may occur in result of welding processes, however, they are accompanied by great numbers of iron and iron oxide spherules. Thus, with this analytical method a population of welding particles can be distinguished from a population of gunshot residue originating from a modern type of ammunition, but a special care has to be taken when assessing the evidential value of single or few spherules consisting from light elements being detected in result of the search for gunshot residue for forensic purposes. [ABSTRACT FROM AUTHOR]

Little is known about the persistence of gunshot residue (GSR) in soft tissue and bones during decomposition in marine environments. For a better understanding, qualitative and quantitative data were obtained on GSR retention on soft tissue and bony gunshot wounds (GSWs). A quantity of 36 fleshed and 36 defleshed bovine ribs were shot at contact range with 0.22 calibre hollow point ammunition using a Stirling 0.22 calibre long rifle. Bone specimens in triplicate were placed in three environments: submerged, intertidal and in supralittoral zone. Sets of triplicates were recovered on day 3, 10, 24 and 38, and analysed with scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), and inductive coupled plasma mass spectrometry (ICP-MS). The SEM-EDX recorded GSR-indicative particles surrounding the bullet entrance on all bone types (fleshed and defleshed) in all environments throughout the study. GSR-unique particles were only detected on the supralittoral bones. The ICP-MS analysis showed faster GSR loss on submerged than intertidal and supralittoral defleshed specimens. Fleshed specimens showed a faster GSR loss on intertidal than submerged and supralittoral specimens. In conclusion, the GSR disappeared faster from submerged and intertidal than non-submerged specimens. The difference of detection of GSR between analysed specimens (defleshed versus fleshed) disappeared upon defleshing. This study highlights the potential of finding evidence of GSR in a submerged body and the potential of microscopic and analytical methods for examining suspected GSW in highly decomposed bodies in marine habitats. [ABSTRACT FROM AUTHOR]

A rapid method for the characterization of both organic and inorganic components of gunshot residues (GSR) is proposed as an alternative tool to facilitate the identification of a suspected shooter. In this study, two fast screening methods were developed and optimized for the detection of organic compounds and inorganic components indicative of GSR presence on the hands of shooters and non-shooters. The proposed methods consist of headspace extraction of volatile organic compounds using a capillary microextraction of volatiles (CMV) device previously reported as a high-efficiency sampler followed by detection by GC–MS. This novel sampling technique has the potential to yield fast results (< 2 min sampling) and high sensitivity capable of detecting 3 ng of diphenylamine (DPA) and 8 ng of nitroglycerine (NG). Direct analysis of the headspace of over 50 swabs collected from the hands of suspected shooters (and non-shooters) provides information regarding VOCs present on their hands. In addition, a fast laser induced breakdown spectroscopy (LIBS) screening method for the detection of the inorganic components indicative of the presence of GSR (Sb, Pb and Ba) is described. The sampling method for the inorganics consists of liquid extraction of the target elements from the same cotton swabs (previously analyzed for VOCs) and an additional 30 swab samples followed by spiking 1 μL of the extract solution onto a Teflon disk and then analyzed by LIBS. Advantages of LIBS include fast analysis (~ 12 s per sample) and high selectivity and sensitivity, with expected LODs 0.1–18 ng for each of the target elements after sampling. The analytical performance of the LIBS method is also compared to previously reported methods (inductively coupled plasma–optical emission spectroscopy). The combination of fast CMV sampling, unambiguous organic compound identification with GC–MS and fast LIBS analysis provides the basis for a new comprehensive screening method for GSR. [ABSTRACT FROM AUTHOR]

When reporting results of Gunshot Residue (GSR) analysis from a person suspected to be involved in a recent shooting, most forensic experts only provide the court with the raw results (i.e. the number of GSR particles found) and a disclaimer that a positive finding does not prove that the suspect was involved in a firearm shooting incident whilst a negative finding does not prove that he was not. Probabilistic analysis of the GSR results provides more value to the court, so the present study calculated likelihood ratio (LR) values for finding 0-8 characteristic GSR particles (containing Lead, Barium and Antimony) on a suspect's hands, based on the available GSR data from the published literature as well as studies by the authors. Defense propositions, i.e. modes for GSR acquisition other than involvement in a shooting event, were divided into three broad categories: low, medium and heavy background. For each background level and number of GSR particles found, minimal and maximal LR values were calculated. Thus, for each proposition the defense provides for the presence of GSR on the defendant's hands, the forensic expert can provide a possible set of minimal and maximal LR values, leaving the court to examine the defendant's contention and decide which of the three background modes is more plausible according to the circumstances of the specific case. [ABSTRACT FROM AUTHOR]

Chemical evaluation of gunshot residues (GSR) produced by non-toxic lead-free ammunition (NTA) has been a challenge to forensic analyses. Our group developed some luminescent markers specific to the detection of GSR. Here, we evaluated the performance of selected markers in experiments that mimic forensic context and/or routines in which luminescent characteristics would be very useful. We evaluated the influence of markers' addition on the bullet's speed, the rate of shot failure (i.e., when the cartridge case is not fully ejected and/or a new ammunition is not automatically replaced in the gun chamber) as a function of marker percentage, the possibility of collecting luminescent gunshot residue (LGSR) in unconventional locations (e.g. the shooters' nostrils), the LGSR lifetime after hand washing, the transfer of LGSR to objects handled by the shooter, and the dispersion of LGSR at the crime scene and on simulated victims. It was observed that high amounts of marker (10 wt%) cause high rates of failure on pistols, as well as a substantial decrease in bullet speed. However, the use of 2 wt% of marker minimizes these effects and allows LGSR detection, collection and analysis. Moreover, in all conditions tested, markers showed high performance and provided important information for forensic analyses. For instance, the LGSR particles were found on the floor, ranging from 0 to 9.4 m away from the shooter, on the door panel and seats after a car shooting experiment, and were found easily on a pig leg used to simulate a victim. When a selective tagging was done, it was possible to obtain positive or negative correlation between the victim and shooter. Additionally LGSR possesses a fairly long lifetime (9 h) and good resistance to hand washing (up to 16 washes). [ABSTRACT FROM AUTHOR]

Abstract: Better understanding of gunshot residues and the major elemental composition would be valuable to forensic scientists for their analysis work and interpretation of results. In the present work, the effective atomic numbers of gunshot residues (cartridge case, bullet core, bullet jacket and gunpowder) were analyzed using energy dispersive X-ray analysis (EDX). The scattering of 59.54keV gamma rays is studied using a high-resolution HPGe detector. The experiment is performed on various elements with atomic number in the 4≤Z≤82. The intensity ratio of coherent to Compton scattered peaks, corrected for photo-peak efficiency of gamma detector and absorption of photons in the sample and air, is plotted as a function of atomic number and constituted a best-fit-curve. From this fit-curve, the respective effective atomic numbers of gunshot residues are determined. [Copyright &y& Elsevier]

Gunshot residues (GSR) from a total of nine different caliber ammunitions produced in Brazil were analyzed and characterized by transmission (TEM) and scanning electron microscopy (SEM). GSR particles are composed of spherical particles of several micrometers of diameter containing distinct amounts of lead, bariumand antimony, along with other organic and inorganic elements arising from the primer, gunpowder, the gun and the bullet itself. This study was carried out to obtain additional information on the properties of GSR nanoparticles originated from different types of regular ammunition produced in Brazil by CBC. Besides the SEM, we have used a TEM, exploring its high magnification capability and ability to explore internal structure and chemical composition of submicron particles. We observed that CBC ammunition generated smaller particles than usually reported for other ammunitions and that the three component particles are not a majority. TEM analysis revealed that GSR are partially composed of sub-micron particles as well. The electron diffraction pattern from these particles confirmed them to be mainly composed of lead oxides crystalline nanoparticles that may be agglomerated into larger particles. Energy dispersive X-ray spectroscopy revealed that most of them were composed of two elements, especially PbSb. Ba was not a common element found in the nanoparticles. [ABSTRACT FROM AUTHOR]

In a previous study by Grima et al. Sci. Justice 52 (1) (2012) 49, it was shown that background particles can aid in the exclusion of firework particles which are indistinguishable from GSR. Issues relating to the persistence of such particle populations were presented. The scope of this project was to examine persistence on the hands in the context of possible post-display scene contamination and how this can affect GSR evidence, especially in light of possible GSR/firework mixtures. Persistence was investigated by recovering firework residues eight hours post-display following contact of the hands with bedding. In addition, particle profiling was carried out using SEM-EDX. Firework particle populations exhibited strong persistence in all displays, with not less than 667 particles persisting in each scenario. This factor challenges GSR evidence, especially if personnel stationed at display sites enter scenes of crime or come into contact with suspects after a display. A survey of UK police force practices following firework displays showed that authorities are not aware of the impact particle transfer may have on GSR evidence. Recommendations for the implementation of basic hygiene practices for particle transfer control have also been made. [ABSTRACT FROM AUTHOR]

The study was designed to obtain a comprehensive view on the prevalence of gunshot residue and the factors influencing their dispersion. 273 specimens collected from people of various professions, representing both users and non-users of firearms, as well as from the interior of a forensic laboratory were examined for the presence of gunshot residue. In specimens taken from hands of 100 people declaring no contact with firearms only one spherical particle containing lead, antimony and barium was found. Numbers of particles found in specimens collected from hands of 50 shooters varied from zero to numbers greater than 100 and were strongly correlated with the time interval between last shooting and collecting specimens. Within the first 4 h after shooting particles are being lost from the shooter's hands, and so transferred from shooters to their environment. Thus, the relatives of five hunters were examined during both the close and open hunting seasons to trace the potential secondary transfer in practice. Using the criterion of low risk of contamination with gunshot residue, i.e. 5 h after last handling a gun, only few specimens were encountered among these collected from hands of firearm users that contained characteristic particles and these occurred in small numbers. Frequent shooters, e.g. shooting instructors or firearm examiners, formed a class for themselves of high risk of contamination with gunshot residue. As a result of continuous monitoring of the laboratory (55 specimens examined so far), where the examinations of gunshot residue are being carried out, it has been proved that the laboratory is free from contamination and so confirmed the usefulness of protocols worked out. The obtained information provided empirical bases to the minimisation of the risk of contamination of the evidence as well as for the evaluation of the analytical findings in the expertise on gunshot incidents. [ABSTRACT FROM AUTHOR]

A comprehensive review was conducted on 42 closed court cases for which at least one gunshot residue (GSR) expertise had been requested. The aim of this study is to examine the use and understanding of the GSR findings by criminal justice professionals, the contribution to/relationship with other (forensic) elements of the case, and ultimately to assess the place of the GSR expertise in judicial decisions. The study shows that, in the vast majority of cases, the court appeared to interpret and use the GSR findings correctly, although some minor misuses were identified, mainly when the court incorrectly mentioned the expert's words, using the prosecutor's fallacy. In the end, a higher percentage of conviction rate (+23% points) was observed when incriminating GSR findings were obtained. Surprisingly, in half of the cases examined in which a guilty verdict was reached, GSR evidence was the only forensic evidence in the file. [ABSTRACT FROM AUTHOR]

Comparative gunshot residue analysis addresses relevant forensic questions such as 'did suspect X fire shot Y?'. More formally, it weighs the evidence for hypotheses of the form H1: gunshot residue particles found on suspect's hands are from the same source as the gunshot residue particles found on the crime scene and H2: two sets of particles are from different sources. Currently, experts perform this analysis by evaluating the elemental composition of the particles using their knowledge and experience. The aim of this study is to construct a likelihood-ratio (LR) system based on representative data. Such an LR system can support the expert by making the interpretation of the results of electron microscopy analysis more empirically grounded. In this study we chose statistical models from the machine learning literature as candidates to construct this system, as these models have been shown to work well for large and high-dimensional datasets. Using a subsequent calibration step ensured that the system outputs well-calibrated LRs. The system is developed and validated on casework data and an additional validation step is performed on an independent dataset of cartridge data. The results show that the system performs well on both datasets. We discuss future work needed before the method can be implemented in casework. [ABSTRACT FROM AUTHOR]

A quantitative study of common forensic evidence collection devices for the recovery of low-explosive residues from non-porous glass and plastic is presented herein. Swabbing materials including cotton, rayon, Nomex® (poly(isophthaloylchloride/m-phenylenediamine)), Teflon/Teflon-coated fibreglass (polytetrafluoroethylene) and adhesive-coated tapes were used to collect known quantities of up to 14 forensically relevant inorganic and organic anion and cation species from both surfaces. Analysis was performed using two validated ion chromatography methods. This study revealed that all swabs and surfaces contributed highly variable levels of interfering ionic species and that swabbing materials showed variance in the quantities and total number of analytes recovered from both surfaces. Teflon and Nomex® materials demonstrated the most promise due to their ability to collect and release analytes into simple extraction solvents as well as displaying relatively low endogenous interference. In parallel, the ability to extract residue directly from both surfaces via the addition of a suitable extraction solvent was investigated instead of swabbing. This work highlights that direct solvent extraction from a surface should be considered as an alternative approach, especially for small areas or objects. To the best of our knowledge, this work represents the most comprehensive study of the efficiencies of sample collection technologies for low-explosive residues prior to analysis by ion chromatography. [ABSTRACT FROM AUTHOR]

The ability to link criminal activity and identity using validated analytical approaches can be of great value to forensic scientists. Herein, the factors affecting the recovery and detection of inorganic and organic energetic material residues within chemically or physically enhanced fingermarks on paper and glass substrates are presented using micro-bore anion exchange chromatography with suppressed conductivity detection. Fingermarks on both surfaces were enhanced using aluminium powder or ninhydrin after spiking with model test mixtures or through contact with black-powder substitutes. A quantitative study of the effects of environmental/method interferences, the sweat matrix, the surface and the enhancement technique on the relative anion recovery of forensically relevant species is presented. It is shown that the analytical method could detect target analytes at the nanogram level even within excesses of enhancement reagents and their reaction products when using solid phase extraction and/or microfiltration. To our knowledge, this work demonstrates for the first time that ion chromatography can detect anions in energetic materials within fingermarks on two very different surfaces, after operational enhancement techniques commonly used by forensic scientists and police have been applied. [ABSTRACT FROM AUTHOR]

Gunshot residues (GSR) are valuable evidence which provide the forensic analyst with useful information about a crime scene when proper analytical methods are used. Nowadays, the method of choice for analyzing GSR is scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX). However, SEM/EDX presents limitations when the GSR identification of ''non-toxic'' ammunition types is performed. To overcome this drawback, Raman spectroscopy has been recently proposed as a complementary technique to SEM/EDX. However, for the time being, it can only be used in a limited number of casework (e.g. examining the macroscopic GSR produced at short distance over victim's clothes) and further research to know when this technique could support SEM-EDX results is required. In the present work, the memory effect of the weapon, which plays an important role to link the GSR found and the ammunition fired, is studied. Twenty shots were fired at close distance ( ∼30 cm) at paper targets using the same weapon with two different types of ammunition. The first, third, ninth, and twentieth shots were fired with the first ammunition and the shots among them using the second ammunition. The macroscopic GSR produced by the first ammunition were analyzed using Raman spectroscopy. First, the spectra obtained were visually differentiated by taking into account the band at about 1342 cm -1. This first approach shown that in the first shot were no GSR particles from the second ammunition, but 1.5-7.5% of analyzed particles corresponded to the second ammunition in the third, ninth, and twentieth shots. Additionally, the same differentiation was then performed by discriminant analysis using the spectral range from 1800 to 800 cm -1. Although using this second approach only one GSR was identified as the second ammunition, was remarkable that after the shots with different ammunition the GSR obtained shows greater variability. The results obtained suggest that the memory effect of the weapon has not a significant influence when the organic analysis of macroscopic GSR on targets by Raman spectroscopy is performed. [ABSTRACT FROM AUTHOR]

Collection efficiency of gunshot residues (GSR) as a function of the type of fabric was evaluated. For this set of experiments, fabrics with differences in their sheddability were exposed to shootings. The samples were then stubbed to collect GSR following a standard procedure for SEM/EDX analysis. The results show a strong relationship between sheddability and collection efficiency, since the collection efficiency is about five-fold higher for leather compared with wool. The main factor explaining this difference is probably the rate of saturation (for instance by fibres) of the carbon tapes used to stub the fabrics. An example originating from a real case supports this hypothesis. [ABSTRACT FROM AUTHOR]

Abstract: Sample preparation in forensic science offers special challenges in that the sample matrix and the analytes change depending on the circumstances of the case. It is difficult to standardize the sample preparation step for many types of cases due to sample and matrix complexity and the total unknown nature of the target analytes present within the matrix. Secondly, the analytical results obtained from forensic samples often undergo rigorous legal scrutiny and challenges. As such, maintaining the integrity of the sample chain of custody should be considered during the sampling and sample preparation prior to analysis. Finally, for those sample matrices where the sample preparation can be standardized (i.e., fire debris analysis and toxicology), utmost care should be taken to minimize the possible interferents and maximize the analyte concentration to meet the analytical requirements. In this article, we discuss the nature and the types of forensic samples of interest, and recent developments and innovations in micro-sample preparation techniques in different disciplines within forensic science. We also discuss the future outlook of forensic sample preparation. [Copyright &y& Elsevier]

Abstract: Estimating the time since discharge of a spent cartridge or a firearm can be useful in criminal situations involving firearms. The analysis of volatile gunshot residue remaining after shooting using solid-phase microextraction (SPME) followed by gas chromatography (GC) was proposed to meet this objective. However, current interpretative models suffer from several conceptual drawbacks which render them inadequate to assess the evidential value of a given measurement. This paper aims to fill this gap by proposing a logical approach based on the assessment of likelihood ratios. A probabilistic model was thus developed and applied to a hypothetical scenario where alternative hypotheses about the discharge time of a spent cartridge found on a crime scene were forwarded. In order to estimate the parameters required to implement this solution, a non-linear regression model was proposed and applied to real published data. The proposed approach proved to be a valuable method for interpreting aging-related data. [Copyright &y& Elsevier]

The use of micro-CT within forensic practice remains an emerging technology, principally due to its current limited availability to forensic practitioners. This review provides those with little or no previous experience of the potential roles of micro-CT in forensic practice with an illustrated overview of the technology, and the areas of practice in which micro-CT can potentially be applied to enhance forensic investigations. [ABSTRACT FROM AUTHOR]

Abstract: The organic components of gunshot residue (OGSR, also called firearms discharge residue (FDR) or cartridge discharge residue (CDR)) have been studied and discussed in the literature. These residues, consisting of particulates such as burned and unburned powder as well as molecular compounds, are rarely used in casework except for purposes such as shooting reconstructions. Molecular compounds that survive the firing event or that are created as a result of the firing event could, with focused research and development, open a new avenue for forensic gunshot residue analysis. In this study, the persistence of organic gunshot residue was evaluated using diphenylamine (DPA) as a target analyte and ion mobility spectrometry (IMS) as the detection system. Samples were collected from hands using a solvent swabbing technique and the swab was analyzed using direct thermal desorption for sample introduction into the IMS. OGSR was found to persist for at least 4h. Although DPA is a widely used industrial compound, analysis of numerous blank and background samples (n ∼100) did not show any significant response for DPA using this detector. Variations were noted among individuals and as such, the data set does not support estimation of a half-life as has been done for traditional primer residues. No secondary transfers were observed, suggesting the possibility of skin adhesion via interactions between the lipophilic organic compounds and skin lipids. IMS proved valuable as a means of generating patterns for forensic pattern matching and shows promise as a screening tool applied to firearms discharge. [Copyright &y& Elsevier]

Abstract: Gunshot residue (GSR) is commonly analysed in forensic casework using either scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) or gas chromatography-mass spectrometry (GC–MS). Relatively little work has been reported on the post-discharge GSR content of non-metallic inorganic or low molecular weight organic anions to distinguish between different ammunition types. The development of an analytical method using suppressed micro-bore anion exchange chromatography (IC) is presented for the analysis of GSR. A hydroxide gradient was optimised for the separation of 19 forensically relevant organic and inorganic anions in <23min and sensitivities of the order of 0.12–3.52ng of anion detected for all species were achieved. Along with an optimised extraction procedure, this method was applied to the analysis of post-ignition residues from three selected ammunition types. By profiling and comparing the anionic content in each ammunition residue, the possibility to distinguish between each type using their anionic profiles and absolute weight is presented. The potential for interference is also discussed with respect to sample types which are typically problematic in the analysis of GSR using SEM-EDX and GC–MS. To the best of our knowledge this represents the first study on the analysis of inorganic anions in GSR using suppressed ion chromatography. [Copyright &y& Elsevier]

Abstract: Increasing security needs require field-deployable, on-the-spot detection tools for the rapid and reliable identification of gunshot residue (GSR), and thus the collection of GSR samples is a crucial step in forensic analysis. In this work we demonstrate a novel protocol integrating GSR sampling and electroanalysis using microfabricated carbon sensor-strips. The new integrated sampling/detection methodology relies on abrasive stripping voltammetry (AbrSV) involving an initial mechanical transfer of trace amounts of surface-confined GSR from the hand of a suspect directly onto the electrode contingent of the sensor strip, which is immediately ready for electrochemical analysis. The integrated sampling/detection method holds much promise as a portable, rapid and inexpensive system to promptly identify a subject who has discharged a firearm in various forensic scenarios. [Copyright &y& Elsevier]

Abstract: The presence of gunshot residues (GSRs) on arrested suspects can help the Court to form an opinion regarding the possibility of utilization of firearms by these suspects. Since the presence of a few particles can in some cases already have a strong indicative value, the GSR experts have to evaluate in their daily work the risk of a potential contamination of these suspects during their arrest. A few studies conducted on police officers and police facilities concluded that the risk of secondary transfer on arrested suspects is quite negligible. However, the case of special force units of the police should be taken into account, since these units can be assumed to be highly contaminated by GSR due to their intensive training. The aim of this study is to evaluate this possibility of particle transfer by performing simulations of arrests by special force police units, according to both low and high contamination scenarios. The results show that secondary transfers of GSR during these simulations are in most cases not negligible, even for the low contamination scenario. This is especially apparent on the vests of the target persons, with an average of 7 GSR particles (2 PbBaSb and 5 TiZn) found on the stubs used on these materials. Of course, the major contamination levels were observed in the case of the high contamination scenario, due to the use of highly contaminated gloves by the police officers during the arrests. Some recommendations are proposed to take into account this risk of contamination and to try to minimize it, or at least to better identify it. [Copyright &y& Elsevier]

Abstract: Electrochemical lead analyses of gunshot residues (GSRs) were performed using an acidic solution with a bare gold microelectrode in the presence of chloride ions. GSRs from four different guns (0.38in. revolver, 12 caliber pump-action shotgun, 0.38 repeating rifle, and a 0.22 caliber semi-automatic rifle) and six different types of ammunition (CleanRange®, normal, semi-jacketed, especial 24g®, 3T®, CBC®, and Eley®) were analyzed. Results obtained with the proposed methodology were compared with those from an atomic absorption spectrometry analysis, and a paired Student''s t-test indicated that there was no significant difference between them at the 95% confidence level. With this methodology, a detection limit of 1.7nmolL−1 (3σ/slope), a linear range between 10 and 100nmolL−1, and a relative standard deviation of 2.5% from 10 measurements were obtained. [Copyright &y& Elsevier]