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ABSTRACT Vibrational spectroscopy combined with machine learning has a great potential for forensic applications. For example, handheld Raman spectroscopic instruments are already used by law enforcement agencies for precise, confirmatory identification of drugs. Beyond drug identification, several emerging technologies based on vibrational spectroscopy are currently under development for forensic investigative purposes, including the analysis of questioned documents, gunshot residue, fabrics, soil, hair, nails, and nail polish. This article provides a comprehensive overview of the application of vibrational spectroscopy in various areas of forensic analysis, particularly focusing on forensic serology and the analysis of trace evidences. In the case of forensic serology, the methodology allows for determining complex aspects of serological casework, including the time since deposition of a stain, as well as the phenotypic profile of the stain donor—namely, sex, race, and age. Furthermore, gunshot residues can be accurately identified by grain, caliber, and manufacturer when Raman spectroscopy is paired with machine learning. This integration of advanced spectroscopic techniques with machine learning holds great promise for furthering both the accuracy and efficiency of investigations, helping to reduce the total backlog of evidence investigation currently plaguing modern forensic laboratories. [ABSTRACT FROM AUTHOR]

Inorganic gunshot residue (iGSR) analysis, crucial for linking suspects to firearm use, faces challenges from potential environmental contamination, notably in police vehicles. The present study aimed to explore the level of iGSR contamination in police vehicles from the Zagreb County Police Administration (Croatia), considering particle types and their position in vehicles, and to identify associated risk factors. From December 2021 to April 2022, 65 of 86 police vehicles (margin of error: ±6% at a 95% confidence level) were sampled with GSR stubs on the drivers' seats, back seats, and backrests and analyzed using scanning electron microscopy and energy dispersive x‐ray analysis (SEM/EDX). Characteristic particles were found in 63.1% of vehicles, 33.8% on the driver's seat, and 24.6% on the back seat/backrest. Indicative particles were found in 70.77% of vehicles, with a fairly even distribution. McNemar's chi‐square analysis showed no significant disparities in positive sample ratios across vehicle parts or particle types (p > 0.05). In total, 228 characteristic and 166 indicative GSR particles were identified, with no notable correlation among them (p = 0.346). Logistic regression analysis identified the transportation of individuals involved in firearms incidents as a statistically significant factor influencing the presence of characteristic particles (p = 0.030). The findings suggest a considerable prevalence of iGSR in the analyzed Police Administration unit, highlighting the need for careful contamination management in police operations to preserve evidence integrity, particularly in cases when individuals who used firearms had been transported in the vehicle. [ABSTRACT FROM AUTHOR]

The presence of gunshot residue (GSR) in a sample can provide valuable information in forensic investigations by associating a suspect with a shooting incident. However, in order to have confidence in the integrity of the results' interpretation, the possibility of contamination by secondary transfer of GSR occurring during the transportation of a person under custody in a police vehicle should be evaluated. In order to investigate police vehicles as a source for secondary transfer of GSR particles, a total of 51 samples were collected from the rear seats of random police vehicles and used to transport arrested individuals. Results indicated that the type of upholstery of the seats plays a main role in determining the potential for secondary GSR contamination. The potential chance of coming into contact with GSR particles in police vehicles is low. GSR contamination from police vehicles is, maybe, not of a major concern but should be taken into consideration mainly when very few characteristic GSR particles are found on an analyzed sample. [ABSTRACT FROM AUTHOR]

In this work, we present a compact LIBS sensor developed for characterization of samples on a crime scene following requirements of law enforcement agencies involved in the project. The sensor operates both in a tabletop mode, for aside measurements of swabbed materials or taken fragments, and in handheld mode where the sensor head is pointed directly on targets at the scene. The sensor head is connected via an umbilical to an instrument box that could be battery-powered and contains also a color camera for sample visualization, illumination LEDs, and pointing system for placing the target in focus. Here we describe the sensor's architecture and functionalities, the optimization of the acquisition parameters, and the results of some LIBS measurements. On nano-plotted traces at silica wafer and in optimized conditions, for most of the elements the detection limits, in term of the absolute element masses, were found to be below 10 picograms. We also show results obtained on some representative materials, like fingerprints, swabbed soil and gunshot residue, varnishes on metal, and coated plastics. The last, solid samples were used to evaluate the depth profiling capabilities of the instrument, where the recognition of all four car paint layers was achieved. [ABSTRACT FROM AUTHOR]

It is a well-established fact that legally sound evidences are required to prove or disprove any criminal activity. When a particular activity occurs, it leaves a trace out of mutual contact and failure to detect that trace proves the activity did not occur. To enhance the capabilities of the justice system in evaluating evidence, researchers are continuously engaged in the development of novel analytical techniques which provide scientific methodologies for effectively assessing and interpreting the evidence associated with criminal activities. Among the several devices available, paper-based microanalytical devices (μPADs) have attracted the interest of forensic scientists/experts in recent years. These devices are designed with microchannels to which dedicated reagents are added for promoting selective reactions. As a result, they offer a practical and convenient solution for on-site detection of physical evidence, providing ready-to-use capabilities for forensic investigations. This does not only help the investigators in collection of legally sound evidences but also open avenues in apprehending the potential offender who might be present in the scene by detecting the traces. μPADs are inexpensive, simpler to operate, require less chemical consumption, portable, and provides results visible to naked eye. Furthermore, with the aid of digital scoring of color intensity, semi-quantitative results can be generated. This review explains current state of applications and operating chemistry of µPADs involved in analysis of evidences of forensic interest such as explosives, gunshot residue, drugs of abuse, pesticides, body fluids, and estimation of time since death. Furthermore, the research gaps in the domain and viability of future trends for the application of µPADs in forensic science are also presented. [ABSTRACT FROM AUTHOR]

The automated search software integrated with a scanning electron microscope (SEM/EDS) has been the standard tool for detecting inorganic gunshot residues (iGSR) for several decades. The detection of these particles depends on various factors such as collection, preservation, contamination with organic matter, and the method for sample analysis. This article focuses on the influence of equipment resolution setup on the backscattered electron images of the sample. The pixel size of these images plays a crucial role in determining the detectability of iGSR particles, especially those with sizes close to the pixel size. In this study, we calculated the probability of missing all characteristic iGSR particles in a sample using an SEM/EDS automated search and how it depends on the image pixel resolution setup. We developed and validated an iGSR particle detection model that links particle size with equipment registers and applied it to 320 samples analyzed by a forensic science laboratory. Our results show that the probability of missing all characteristic iGSR particles due to their size is below 5% for pixel sizes below 0.32 μm2. These findings indicate that pixel sizes as large as twice the one commonly used in laboratory casework, that is, 0.16 μm2, are effective for initial sample scanning, yielding good detection rates of characteristic particles that could exponentially reduce laboratory workload. [ABSTRACT FROM AUTHOR]

At present, it is challenging to accurately determine firearm shooting distances in the case that lead-free ammunition is involved, largely because different manufacturers use different primer compositions. Laser-induced breakdown spectroscopy (LIBS) allows the simultaneous detection of multiple elements with high sensitivity and so may represent a solution to this problem. Previous studies have, in fact, demonstrated that LIBS can be used to determine shooting distances when working with gunshot residues from conventional ammunition based on scanning fabric surfaces. The present study confirms that the shooting distance can be ascertained using LIBS to detect copper originating from the ammunition casing and projectile but not the primer on fabric surfaces. This estimation can be performed regardless of the primer composition of lead-free ammunition. Key points Evaluation of gunshot residue from lead-free ammunition using scanning electron microscopy-energy dispersive X-ray analysis indicated that 40% of the particles contained copper. The iForenLIBS system allowed the detection of copper-containing particles on fabric surfaces after firing at different distances with high sensitivity. Laser-induced breakdown spectroscopy can determine the shooting distance of lead-free ammunition through copper detection even in ammunition that does not used this element in the primer. This technique can generate density maps allowing the evaluation of short, medium, and long-range shooting distances. [ABSTRACT FROM AUTHOR]

The characterization of firearm discharge residue (FDR) as a piece of evidence plays an essential role in interpreting the forensic cases involving the use of firearms, such as robberies, murders, suicides, and serious attacks. In the last decade, modern or non-toxic primers have emerged due to environmental issues. Forensic examination of gunshot residue (GSR) has become challenging as primer compositions now vary greatly. The goal of this paper is to provide the elemental profiling of both toxic and lead-free cartridge primers available in the Turkish ammunition market. Inductively coupled plasma-mass spectrometry (ICP-MS), scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDS), and X-ray photoelectron spectroscopy (XPS) were used in this investigation. Multivariate statistical methodologies such as principal component analysis (PCA) and Pearson's correlation coefficient (PCC) analysis were used to interpret the elemental profile data determined in the residue generated after ignition of the cartridge primers. Three components were observed: Ba-Sb-Pb-Cu-Gd, Ti-Sr-Zn, and Al-Ca-Ga, which is also consistent with the PCC analysis. SEM-EDS was employed to confirm the existence of GSR particles. The binding energies, determined using XPS, indicated the chemical state assignments in samples such as Pb(NO3)2, Sb2S3, Ba(NO3)2, CuO, ZnO and MoS2. This research will improve the robustness of the interpretation of GSR-related evidence. [ABSTRACT FROM AUTHOR]

This study describes the use of single particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) for the detection and classification of inorganic gunshot residue (IGSR) particles. To establish reliable multi-element criteria to classify IGSR particles, leaded and lead-free IGSR reference materials were analyzed, and the elemental compositions of the individual particles were quantified. The results suggest that expanded element compositions may be used to classify IGSR particles via spICP-TOFMS compared to those used in conventional IGSR analysis using scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS). For spICP-TOFMS analysis of leaded IGSR particles, classification may be based on the presence of lead (Pb), antimony (Sb), and barium (Ba) just as in SEM-EDS; however, additional particle types, such as lead-copper (Pb–Cu) particles, contribute significantly (∼30%) to the leaded IGSR particle population. In lead-free IGSR particles, the dominate multi-metal particle composition found is titanium–zinc (Ti–Zn) with a conserved Zn:Ti ratio of 1.4:1, but other elements, such as copper (Cu), are also characteristic. In mixtures of the two IGSR reference materials, we were able to classify over 80% of the multi-metal particles detected with no false-positive particle-type assignments. With spICP-TOFMS, particles smaller than those typically measured by SEM-EDS are detected, with estimated median diameters for leaded and lead-free IGSR of 180 and 320 nm, respectively. Through measuring these smaller particles, up to ∼two times more particles per mL are recorded by spICP-TOFMS compared to that found by SEM-EDS. Overall, high-sensitivity and high-throughput analysis using spICP-TOFMS enables quantitative, rapid multi-elemental characterization, and classification of individual IGSR particles. Graphical Abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

The identification of firearms is of paramount importance for investigating crimes involving firearms, as it establishes the link between a particular firearm and firearm-related elements found at a crime scene, such as projectiles and cartridge cases. This identification relies on the visual comparison of such elements against reference samples from suspect firearms or those existing in databases. Whenever this approach is not possible, the chemical analysis of the gunpowder and gunshot residue can provide additional information that may assist in establishing a link between samples retrieved at a crime scene and those from a suspect or in the identification of the corresponding model and manufacturer of the ammunition used. The most commonly used method for the chemical analysis of gunshot residue is scanning electron microscopy with energy dispersive X-ray, which focuses on the inorganic elements present in ammunition formulation, particularly heavy metals. However, a change in the legal paradigm is pushing changes in these formulations to remove heavy metals due to their potential for environmental contamination and the health hazards they represent. For this reason, the importance of the analysis of organic compounds is leading to the adoption of a different set of analytical methodologies, mostly based on spectroscopy and chromatography. This manuscript reviews the constitution of primer and gunpowder formulations and the analytical methods currently used for detecting, characterising, and identifying their compounds. In addition, this contribution also explores how the information provided by these methodologies can be used in ammunition identification and how it is driving the development of novel applications within forensic ballistics. [ABSTRACT FROM AUTHOR]

Abstract Background The forms and compositions of primer gunshot residue (GSR) in shooting cases have been routinely analyzed in many crime labs by scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS). Gunshot residue studies over the last 30 years have identified a contribution by residual GSR from surfaces within the firearm to GSR (the “memory effect”). In this study, we first focus on the GSR compositional differences between target, bore, and cylinder gap for a .22 caliber revolver which has received little attention in the literature. Secondly, we examine the behavior of elements involved in the residual contribution to GSR for a .22 caliber pistol. Results The compositions of target, bore, and cylinder gap GSRs from a .22 caliber revolver were determined for 11 discharge series. Breech GSR compositions from a .22 caliber pistol changed in sequential discharges revealing behavior of individual primer and bullet elements. The target GSR forms from some .22 caliber ammunitions were not spherical. Conclusions For the revolver, GSR compositions from the target, bore, and cylinder gap are divergent. Analysis of the pistol’s breech GSRs indicated mixing with the previously deposited GSRs resulting in a sequential contribution or loss of elements and redeposition of the new composition. Aluminum did not contribute to the residual GSR. The GSR composition of a discharge and its contribution to residual GSR on the internal parts of the firearm represents a complex process which likely involves a number of variables including, but not restricted to firearm design, primer composition, pressure and temperature of the discharge gas, and bullet surface composition.

Gunshot residues (GSR) are one of the most important forensic traces in crimes involving firearm discharge, being the conventional GSR characterized by containing spheroidal particles composed of Pb, Ba, and Sb. Over the years, a wide range of techniques has been applied and improved to characterize the conventional GSR, with deserved emphasis on scanning electron microscopy coupled with energy‐dispersive x‐ray spectroscopy (SEM/EDS). However, the introduction of nontoxic ammunition (NTA), or heavy metal‐free (HMF), on the market has triggered a search for new methodologies for GSR identification since methods based on the chemical and/or morphological profiles of conventional GSR are no longer appropriate for the analysis of this type of residues. This review highlights current methods and proposals for characterization of GSR from NTA, which involve either the search for characteristic chemical profiles or the insertion of selective markers in this new type of ammunition. This article is categorized under:Forensic Chemistry and Trace Evidence > Emerging Technologies and MethodsForensic Medicine > Imaging Modalities [ABSTRACT FROM AUTHOR]

Currently, SEM‐EDS is used to detect gunshot residue (GSR) from the presence of Ba, Pb, and Sb in the sample. However, the development of new nontoxic ammunition (NTA) has prevented conventional metals from being found. In this work, we aim to determine the presence of an inorganic luminescent chemical marker based on rare earth in gunshot residues using the technique of squarewave voltammetry (SWV). After firing, the luminescent complex [(Eu2Zr)(btc)3(Hbtc)0.5.6H2O], which is used as a chemical marker, can be detected under a UV lamp. An aqueous solution with 0.1 mol L−1 KCl as supporting electrolyte can be easily collected on carbon paste electrode surfaces for SWV analysis A = 100 mV, f = 10 Hz, and step potential of 5 mV are required. The luminescent marker incorporated into the carbon paste electrode showed two anodic peak currents in the region of 0.4 V (vs Ag/AgCl) and at 0.75 V (vs Ag/AgCl) and also a cathodic one in 0.4 V (vs Ag/AgCl). SEM‐EDS was able to analyze the same voltammetric results for conventional and nontoxic ammunition containing the luminescent marker. Therefore, voltammetry and SEM‐EDS are valid for detecting the new residue marker in GSR. Despite this, the electrochemical method is still more advantageous because of its low cost and lack of expensive equipment and supplies in forensic laboratories. [ABSTRACT FROM AUTHOR]

• 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]

Background: The forms and compositions of primer gunshot residue (GSR) in shooting cases have been routinely analyzed in many crime labs by scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS). Gunshot residue studies over the last 30 years have identified a contribution by residual GSR from surfaces within the firearm to GSR (the "memory effect"). In this study, we first focus on the GSR compositional differences between target, bore, and cylinder gap for a.22 caliber revolver which has received little attention in the literature. Secondly, we examine the behavior of elements involved in the residual contribution to GSR for a.22 caliber pistol. Results: The compositions of target, bore, and cylinder gap GSRs from a.22 caliber revolver were determined for 11 discharge series. Breech GSR compositions from a.22 caliber pistol changed in sequential discharges revealing behavior of individual primer and bullet elements. The target GSR forms from some.22 caliber ammunitions were not spherical. Conclusions: For the revolver, GSR compositions from the target, bore, and cylinder gap are divergent. Analysis of the pistol's breech GSRs indicated mixing with the previously deposited GSRs resulting in a sequential contribution or loss of elements and redeposition of the new composition. Aluminum did not contribute to the residual GSR. The GSR composition of a discharge and its contribution to residual GSR on the internal parts of the firearm represents a complex process which likely involves a number of variables including, but not restricted to firearm design, primer composition, pressure and temperature of the discharge gas, and bullet surface composition. [ABSTRACT FROM AUTHOR]

Gunshot residue (GSR) is an important type of forensic trace evidence produced when a firearm is discharged. Currently, inorganic GSR particles are used for establishing the fact of shooting. The organic gunshot residue (OGSR) has been recently shown to have great potential for providing additional information vital for the crime scene investigation. Smokeless powder is the precursor to OGSR and one of its chemical components. In this study, Raman spectroscopy and chemometric modeling were used to analyze smokeless powder extracted from ammunition cartridge cases. The proposed hierarchical model demonstrated great potential for determining the manufacture and the bullet type based on the analysis of smokeless powder. Expanding the developed approach to the analysis of OGSR will be needed to make it a useful tool for law enforcement agencies. [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]

Gunshot residue (GSR) and deoxyribonucleic acid (DNA) analyses are used in the reconstruction of shooting incidents involving firearms. In both fields, adhesive tapes are commonly applied to recover traces. Using a simultaneous sampling approach for retrieving both types of traces from objects related to a shooting can be powerful. We present the results for DNA testing and GSR analysis using "DNA stubs" to recover both types of traces in one sampling. The analyses are successive: stubs are first examined with scanning electron microscopy for the presence of GSR and next subjected to DNA extraction and short tandem repeat (STR) typing. The results show no negative effect on the DNA and GSR results. The risk of DNA contamination during GSR analysis is addressed, showing that it is negligible. Our experiences in casework show that the approach can be successfully implemented. [ABSTRACT FROM AUTHOR]

Abstract Background The determination of the shooting distance using gunshot residue (GSR) analysis is crucial in the investigation and reconstruction of firearm-related crimes. However, the conventional chemographic method for GSR analysis is destructive and has limited sensitivity and selectivity. While the spectroscopic method has potential in GSR analysis for crime investigation, there is a current lack of consistency in the spectroscopic results obtained for shooting distance estimation via GSR analysis. Addressing such limitations will enhance the forensic capabilities of law enforcement and provide an added advantage to crime laboratories during an investigation. It will also reinforce the use of such spectroscopic data in a criminal investigation. Main text We obtained all peer-reviewed articles relevant to shooting distance estimation from searching Scopus, Web of Science, PubMed, and Google Scholar databases. We specifically searched the databases using the keywords “shooting distance,” “range of fire,” “gunshot residue,” “firearm discharge residue,” and “firearm-related crime” and obtained 3811 records. We further filtered these records using a combination of two basic keywords “gunshot residue” and “shooting distance estimations” yielding 108 papers. Following a careful evaluation of the titles, abstracts, and full texts, 40 original peer-reviewed articles on shooting distance estimation via GSR analysis were included in the study. The forgoing included additional sources (n = 5) we obtained from looking through the reference lists of the forensic articles we found. Short conclusion This paper discusses the current scope of research concerning the chemographic and spectroscopic analysis of GSR for shooting distance estimation. It also examines the challenges of these techniques and provides recommendations for future research.

The female victim died 17 h after the discharge of a.38 caliber unjacketed bullet into the temporal bone above her right ear. Her boyfriend was accused of homicide and convicted. The victim was able to affect coordinated movements for some seconds after her devastating head wound. Her post shooting movements were documented by bloodstains. Two forensic pathologists where mistaken in calling gunpowder stippling on the victim’s scalp as suture punctate wounds. The ruptured right meningeal artery was spurting. Blowback spatter transitioned into the arterial spurting spatter as the victim fell to the floor. The post-shooting movements of the victim created stains that confused two bloodstain experts who believed the victim could not move after her cranial wounding. The victim’s hair sample, taken by the emergency room doctor, lacked chain and was subsampled by an unknown party prior to chemical gunshot residue (GSR) testing. The tests were negative which led to the erroneous conclusion the shot was from a distance. The mishandling of the hair sample was not discovered until after trial. A GSR expert testified that the airborne GSR settles in seconds in an enclosed area. However, later publications concluded GSR remains airborne for many minutes. The GSR contamination of the defendant was instrumental in his conviction. The GSR expert never informed the DA or the Court of his error. The evidence indicates the victim’s gunshot wound was self inflicted.

The identification of firearms is of paramount importance for investigating crimes involving firearms, as it establishes the link between a particular firearm and firearm-related elements found at a crime scene, such as projectiles and cartridge cases. This identification relies on the visual comparison of such elements against reference samples from suspect firearms or those existing in databases. Whenever this approach is not possible, the chemical analysis of the gunpowder and gunshot residue can provide additional information that may assist in establishing a link between samples retrieved at a crime scene and those from a suspect or in the identification of the corresponding model and manufacturer of the ammunition used. The most commonly used method for the chemical analysis of gunshot residue is scanning electron microscopy with energy dispersive X-ray, which focuses on the inorganic elements present in ammunition formulation, particularly heavy metals. However, a change in the legal paradigm is pushing changes in these formulations to remove heavy metals due to their potential for environmental contamination and the health hazards they represent. For this reason, the importance of the analysis of organic compounds is leading to the adoption of a different set of analytical methodologies, mostly based on spectroscopy and chromatography. This manuscript reviews the constitution of primer and gunpowder formulations and the analytical methods currently used for detecting, characterising, and identifying their compounds. In addition, this contribution also explores how the information provided by these methodologies can be used in ammunition identification and how it is driving the development of novel applications within forensic ballistics.

Headspace solid-phase micro-extraction (SPME) is a promising technique for the characterisation and profiling of gunshot exhausts in spent cartridge casings, especially for health and environmental risk assessments, as well as forensic purposes. To date, however, no comprehensive investigation has been carried out to objectively assess the kinds of compound released during a discharge that can be recovered by this approach, the selectivity of the main commercially available fibres, and their relative performances for the analysis of gunshot exhausts and the discrimination of different ammunition types. This study aimed to fill this gap. Gunshot exhausts in spent cartridge casings from four different ammunition types were analysed by GC–MS, after extraction with four different commercial fibres: 100 μm polydimethylsiloxane (PDMS), 85 μm polyacrylate (PA), 65 μm polydimethylsiloxane/divinylbenzene (DVB), and 85 μm carboxen/polydimethylsiloxane (CAR). Results showed that, overall, a total of 120 analytes could be observed across the cartridges, but the different tested fibres also displayed distinct performances, which were, to some extent, complementary for the characterisation of gunshot exhausts. DVB, in particular, recovered the most compounds simultaneously. On the other hand, the observed variability between measurements was also high, making it a poor candidate for (semi-)quantitative applications (e.g. estimation of time since discharge and/or source profiling). In this regard, PA demonstrated the highest potential for broad use and implementation in multi-purpose methods. [ABSTRACT FROM AUTHOR]

Abstract Background Gunshot residue (GSR) is a shred of important trace evidence which helps forensic scientists solve a huge range of incidents related to firearms. The identification of the shooter to bullet identification from a gunshot wound help reconstruct a scene of the crime. Main body The review of this scientific paper is based on gunshot residue, its composition, and the growing advanced technology which allow us to study about how GSR analysis help to identify and detect residues. Various methods are acquired to identify and analyze organic and inorganic residues present when ammunition is fired. The review highlights the composition of GSR, its collection methods, and analysis part which emphasize on all the methods developed so far. The use of conventional methods including colorimetric and instrumentation-based analysis and advanced technology including electrochemical technique for detecting residues from the last 50 years. Spot tests or chemical tests were performed but they degrade the sample and can sometimes cause hindrance with some other nearby material present at the crime scene. Instrumentation techniques including AAS, ICP-MS, SEM, SEM-EDX, GC, HPLC, etc. are discussed in detail. Mostly advanced electrochemical methods developed are for inorganic gunshot residues (IGSR), but some researchers worked on both residues. Also, the fabricated electrochemical cells are replaced by a single strip-based technique for easy detection. So, to combat these issues, various scientists are moving towards sensor-based methods for rapid and reliable detection. These methods are more user-friendly, sensitive, and cost-effective and provide rapid detection results. Conclusions This review results in the composition of GSR, its collection methods, and analysis using sophisticated methods that emphasize all the methods developed so far and it also culminates the merits and demerits of all detection methods.

Abstract Background Evidence can be defined as the object’s availability and/or information that indicates whether a belief or proposition is true or valid. Gunshot residue (GSR) is an important evidence that can serve many roles in ballistic investigation such as shooting distance, type of firearm and ammunition used in shooting related to GSR. However, due to minimal amount of GSR that can be found in crime scene, suitable methods and technique are required in order to obtain the information from the evidence. This action is also known as evidence recovery. When a firearm is fired, soot or particles are discharged from any opening of the firearm and deposited at the vicinity of point of shooting. Results This study emphasized on the examination of the soot/particles produced and pattern distribution of GSR deposited on white cotton cloth target at varying shooting distances (from 3 to 50 cm) using a video spectral comparator. Pattern distribution and GSR particle density are the main factors in determining the shooting distances in clothing. Principle component analysis (PCA) and hierarchical clustering analysis (HCA) were used to classify firearms; the differences in the GSR pattern distribution are highly recognizable. This study showed that the relationship between the GSR particle dispersion and shooting distance was proportionally linear. The results obtained from the shooting test showed that the diameter of GSR distribution and the amount of residues being deposited from shots fired decreased at distances greater than 21 cm. Conclusion This study will help the investigators in determining the shooting distances and evaluating the firearms used. There is a promising method for examination of GSR pattern on the target material which is also important for firing distance estimation.

Gunshot residue (GSR) is a composite of unburnt and partially burnt particles from various components of firearm ammunition cartridges. GSR is customarily sampled from small, localized spots and analyzed visually and elementally. The conventional analytical methods for localized GSR are most commonly done through a paired scanning electron microscope–energy dispersive X‐ray spectrometer (SEM‐EDS) to look for the presence of lead, barium, and antimony, the inorganic components of ammunition primer. Previous GSR analysis primarily focused on the material deposited on a shooter's hands and used swabbing or adhesive stubs to collect GSR. In this study, total gunshot residue (tGSR) from six types of ammunition was collected from fabric that was shot at a muzzle‐to‐target distance of 15 cm. Subsequently, each tGSR sample was digested in nitric acid and analyzed with total reflection X‐ray fluorescence spectrometry (TXRF). The TXRF technique can simultaneously identify the individual elements in the tGSR and provide absolute elemental quantification. In contrast, EDS scans report the relative elemental compositions of localized GSR samples rather than giving absolute quantitation. This study reliably revealed distinct patterns in six key elements (lead, copper, barium, antimony, iron, and zinc) of tGSR among the ammunition investigated. Elemental profiles were developed from the analyses to represent each ammunition type and the elemental quantities obtained could be used to suggest the category of ammunition that was used. [ABSTRACT FROM AUTHOR]

When a firearm is discharged, the highest concentration of gunshot residue (GSR) is located on a shooter's hands, forearms, and clothing. Currently, collecting GSR from an individual's hands is accomplished with a carbon disk that is submitted for confirmatory analysis in a forensic laboratory. Presumptive chemical tests can be performed in the field, but these tests consume a portion of the GSR particles leaving a reduced amount of evidence available to be collected and sent to a forensic laboratory. An abundance of research exists for detecting GSR particles instantly on different fabrics using an alternate light source (ALS). This study expanded on that research and developed a noninvasive, visual examination to detect GSR on a suspected shooter's hands without destroying or removing any particles prior to collection. The hands of individuals who recently discharged a firearm were examined under a light source between 475 and 530 nm and an infrared (IR) camera. The fluorescent particles observed on a shooter's hands under 520 nm were similar in size and appearance to GSR particles observed on fabrics under an ALS. The fluorescent particles were collected and analyzed for GSR, and the results indicated that GSR particles were present. More testing needs to be conducted to determine if the fluorescent particles observed are inorganic or organic GSR particles. There is also potential to detect GSR under IR light; however, more research needs to be conducted to determine the composition of the particles observed after image enhancement. [ABSTRACT FROM AUTHOR]

Gunshot residue (GSR) has potential negative health effects on humans as a result of inhalation and dermal exposure to the chemical and physical characteristics of GSR such as Pb, Sb, Ba, nitrocellulose, nitroglycerine, and particulate size fraction. Filter (size selective) and double-sided tape (non-size selective) samples collected airborne GSR during single and triple firing of a 0.22 caliber revolver. Dermal exposures were considered using hand swabs and de-leading wipes, designed to remove the heavy metals. The samples underwent analysis to investigate physical (morphology, size distribution, zeta potential), chemical (black carbon and element concentrations), and potential to induce oxidative stress (oxidative potential via the dithiothreitol (DTT) assay). All sample types detected Pb concentrations higher than national ambient air standards. The de-leading wipes reduced the metal content on the hands of the shooter for Pb (15.57 ± 12.99 ppb and 3.13 ± 4.95 ppb). Filter samples provided health relevant data for airborne PM2.5 for all of the analysis methods except for GSR morphology. This work identified collection and analysis methods for GSR in an outdoor setting, providing protocols and considerations for future toxicological studies related to inhalation and dermal exposures to particulate GSR. Future studies should investigate the influence of meteorological factors on GSR exposure in an outdoor setting. [ABSTRACT FROM AUTHOR]

Soot is deposited from 20–30 cm from the muzzle of most handguns and arranged concentrically around the entry wound. We examined a case of a self‐inflicted gunshot wound from a 9‐mm pistol that left an unusual pattern of soot deposition consisting of two circular 3‐mm deposits of soot located 2 cm from the entry wound. Examination of the weapon and test‐firing it against a cloth reproduced the soot deposits, which were caused by two ports on the top of the barrel. Examination of the weapon and comparing the barrel with the entry wound and surrounding skin may provide important information about the type of weapon, the muzzle‐to‐target distance, and atypical soot deposits. [ABSTRACT FROM AUTHOR]

Detection and identification of gunshot residues (GSR) have been used as base evidence in elucidating forensic cases. GSR particles consist of burnt and partially unburned material and contaminate the hands, face, hair, and clothes of the shooter when coming out of the gun. Nowadays, GSR samples are collected from the hands of the suspect and are analyzed routinely in forensic laboratories by the scanning electron microscope/energy dispersive spectroscopy (SEM/EDS) method. GSR particles are comprised of a morphological and specific structure (generally spherical and have a diameter between 0 and 100 μm [occasionally even larger]). In addition, the present studies in the field have claimed that GSR particles during formation are formed under equilibrium surface distribution and are unrelated to morphological dimensional classification. Our contribution to this study is two‐folded. First, this study offers a new approach to identify images of GSR particles by computer vision gathered by SEM/EDS method from the hand of the shooter. Second, it presents open access to the SEM/EDS image data set of the analyzed GSR. During the study, a new data set consisting of 22,408 samples from three different types of MKEK (Mechanical and Chemical Industries Corporation) brand ammunition has been used. It is seen in the results that the computer vision method has been successful in the dimensional classification of GSR. [ABSTRACT FROM AUTHOR]

This review paper covers the forensic-relevant literature in gunshot residue analysis from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Background: The determination of the shooting distance using gunshot residue (GSR) analysis is crucial in the investigation and reconstruction of firearm-related crimes. However, the conventional chemographic method for GSR analysis is destructive and has limited sensitivity and selectivity. While the spectroscopic method has potential in GSR analysis for crime investigation, there is a current lack of consistency in the spectroscopic results obtained for shooting distance estimation via GSR analysis. Addressing such limitations will enhance the forensic capabilities of law enforcement and provide an added advantage to crime laboratories during an investigation. It will also reinforce the use of such spectroscopic data in a criminal investigation. Main text: We obtained all peer-reviewed articles relevant to shooting distance estimation from searching Scopus, Web of Science, PubMed, and Google Scholar databases. We specifically searched the databases using the keywords "shooting distance," "range of fire," "gunshot residue," "firearm discharge residue," and "firearm-related crime" and obtained 3811 records. We further filtered these records using a combination of two basic keywords "gunshot residue" and "shooting distance estimations" yielding 108 papers. Following a careful evaluation of the titles, abstracts, and full texts, 40 original peer-reviewed articles on shooting distance estimation via GSR analysis were included in the study. The forgoing included additional sources (n = 5) we obtained from looking through the reference lists of the forensic articles we found. Short conclusion: This paper discusses the current scope of research concerning the chemographic and spectroscopic analysis of GSR for shooting distance estimation. It also examines the challenges of these techniques and provides recommendations for future research. [ABSTRACT FROM AUTHOR]

Gunshot residue (GSR) is an important type of forensic trace evidence produced when a firearm is discharged. Currently, inorganic GSR particles are used for establishing the fact of shooting. The organic gunshot residue (OGSR) has been recently shown to have great potential for providing additional information vital for the crime scene investigation. Smokeless powder is the precursor to OGSR and one of its chemical components. In this study, Raman spectroscopy and chemometric modeling were used to analyze smokeless powder extracted from ammunition cartridge cases. The proposed hierarchical model demonstrated great potential for determining the manufacture and the bullet type based on the analysis of smokeless powder. Expanding the developed approach to the analysis of OGSR will be needed to make it a useful tool for law enforcement agencies.

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]

Background: Gunshot residue (GSR) is a shred of important trace evidence which helps forensic scientists solve a huge range of incidents related to firearms. The identification of the shooter to bullet identification from a gunshot wound help reconstruct a scene of the crime. Main body: The review of this scientific paper is based on gunshot residue, its composition, and the growing advanced technology which allow us to study about how GSR analysis help to identify and detect residues. Various methods are acquired to identify and analyze organic and inorganic residues present when ammunition is fired. The review highlights the composition of GSR, its collection methods, and analysis part which emphasize on all the methods developed so far. The use of conventional methods including colorimetric and instrumentation-based analysis and advanced technology including electrochemical technique for detecting residues from the last 50 years. Spot tests or chemical tests were performed but they degrade the sample and can sometimes cause hindrance with some other nearby material present at the crime scene. Instrumentation techniques including AAS, ICP-MS, SEM, SEM-EDX, GC, HPLC, etc. are discussed in detail. Mostly advanced electrochemical methods developed are for inorganic gunshot residues (IGSR), but some researchers worked on both residues. Also, the fabricated electrochemical cells are replaced by a single strip-based technique for easy detection. So, to combat these issues, various scientists are moving towards sensor-based methods for rapid and reliable detection. These methods are more user-friendly, sensitive, and cost-effective and provide rapid detection results. Conclusions: This review results in the composition of GSR, its collection methods, and analysis using sophisticated methods that emphasize all the methods developed so far and it also culminates the merits and demerits of all detection methods. [ABSTRACT FROM AUTHOR]

Background: Evidence can be defined as the object's availability and/or information that indicates whether a belief or proposition is true or valid. Gunshot residue (GSR) is an important evidence that can serve many roles in ballistic investigation such as shooting distance, type of firearm and ammunition used in shooting related to GSR. However, due to minimal amount of GSR that can be found in crime scene, suitable methods and technique are required in order to obtain the information from the evidence. This action is also known as evidence recovery. When a firearm is fired, soot or particles are discharged from any opening of the firearm and deposited at the vicinity of point of shooting. Results: This study emphasized on the examination of the soot/particles produced and pattern distribution of GSR deposited on white cotton cloth target at varying shooting distances (from 3 to 50 cm) using a video spectral comparator. Pattern distribution and GSR particle density are the main factors in determining the shooting distances in clothing. Principle component analysis (PCA) and hierarchical clustering analysis (HCA) were used to classify firearms; the differences in the GSR pattern distribution are highly recognizable. This study showed that the relationship between the GSR particle dispersion and shooting distance was proportionally linear. The results obtained from the shooting test showed that the diameter of GSR distribution and the amount of residues being deposited from shots fired decreased at distances greater than 21 cm. Conclusion: This study will help the investigators in determining the shooting distances and evaluating the firearms used. There is a promising method for examination of GSR pattern on the target material which is also important for firing distance estimation. [ABSTRACT FROM AUTHOR]

Entomotoxicology allows the detection and analysis of substances such as poisons, drugs, and metals in necrophagous insects using analytical protocols. In a forensic situation related to death by gunshot, the gunshot residue (GSR) is dispersed at the crime scene and may be consumed by necrophagous insects. Lead (Pb) is the most abundant metal in GSR samples and it can be determined using non-portable methods. However, the toxicity effects of GSR samples on Lucilia cuprina (Diptera: Calliphoridae) and the detection of Pb via portable electrochemical methods have not been investigated. This study describes for the first time the toxicity analysis of Pb on immature L. cuprina through their survival rate and influence of Pb on immature development. In addition, the bioaccumulation of Pb in the larvae samples was determined based on square wave anodic stripping voltammetry (SWASV) measurements. The results revealed a low limit of detection to Pb (6.5 μg L−1) and the analytical performance was satisfactory because it measures Pb levels in larvae exposed to a diet containing 50 μg Pb g−1. Furthermore, the levels of Pb influenced the survival rate and development time of the immature L. cuprina. Larvae exposed to a high concentration of the metal (50 μg Pb g −1) showed statistically significant changes (p < 0.05). The presence of Pb in immature L. cuprina can be used to estimate the post-mortem interval; thus, the present study provides important information in forensic entomology. [ABSTRACT FROM AUTHOR]

Gunshot residue (GSR) stemming from the discharge of firearms has been essential to advancements in the field of forensic science however the human and environmental health impacts from GSR are far less researched. GSR represents a multifaceted concern: it contains a complex mixture of inorganic and organic components and produces airborne particles with variable sizes, depositions, and fates. Herein we evaluate studies in the literature examining GSR collection, deposition, composition, environmental contamination, and potential remediation techniques within the last two decades (2000 – 2020). Throughout we reflect upon key findings and weaknesses in relation to environmental characterization of GSR and associated firearm contaminants. Research focused on techniques to analyze both inorganic and organic GSR simultaneously has begun, but requires additional effort. A vast majority of the available environmental characterization literature focuses on soil contamination at outdoor firing ranges for a select number of elements (Cu, Pb, Sb) with comparisons between ranges or at different collection distances and depths. There is limited ability for between study comparisons due to collection and analysis differences as well as a lack of background soil sampling. Notably, these studies lack direct quantification of the contribution of contaminants from GSR as well as analysis of organic compounds. Currently, there is a need for air monitoring to determine the composition, deposition, and fate of GSR, particularly in outdoor settings. This review summarizes the collection, characterization, and environmental studies related to GSR and highlights areas of research needed to establish the environmental health impacts.

Gunshot residue (GSR) has potential negative health effects on humans as a result of inhalation and dermal exposure to the chemical and physical characteristics of GSR such as Pb, Sb, Ba, nitrocellulose, nitroglycerine, and particulate size fraction. Filter (size selective) and double-sided tape (non-size selective) samples collected airborne GSR during single and triple firing of a 0.22 caliber revolver. Dermal exposures were considered using hand swabs and de-leading wipes, designed to remove the heavy metals. The samples underwent analysis to investigate physical (morphology, size distribution, zeta potential), chemical (black carbon and element concentrations), and potential to induce oxidative stress (oxidative potential via the dithiothreitol (DTT) assay). All sample types detected Pb concentrations higher than national ambient air standards. The de-leading wipes reduced the metal content on the hands of the shooter for Pb (15.57 ± 12.99 ppb and 3.13 ± 4.95 ppb). Filter samples provided health relevant data for airborne PM2.5 for all of the analysis methods except for GSR morphology. This work identified collection and analysis methods for GSR in an outdoor setting, providing protocols and considerations for future toxicological studies related to inhalation and dermal exposures to particulate GSR. Future studies should investigate the influence of meteorological factors on GSR exposure in an outdoor setting.

The surfaces of thirty‐one gunpowders (GPs) from Winchester, Federal, Hercules, DuPont, and Remington were examined by scanning electron microscopy/energy dispersive X‐ray spectroscopy. Particles and surface coatings on 22 of the GPs had compositions of sulfur/potassium/barium or sulfur/potassium detected. Primer‐like particles composed of lead/antimony/barium were found on surfaces of twelve GPs. Gunpowders from fifteen different lots of Winchester 9 mm Silvertip® hollow point cartridges were found to vary in GP type (flake and flattened ball) and associated inorganic compounds of sulfur/potassium/barium or sulfur/potassium or one with only potassium. No inorganic particles or coatings were detected on two of these Winchester GPs. The elements from the inorganic compounds on GPs likely contribute to gunshot residue generated by the discharge of a firearm. [ABSTRACT FROM AUTHOR]