Development and application of a new nose hairs sample collection device for GSR Particles by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS)

Organic and inorganic gunshot residues on the hands, forearms, face, and nostrils of shooters 30 min after a discharge

During the investigation of firearm-related incidents, gunshot residues (GSR) can be collected on the scene and individuals (e.g., shooters or bystanders). Their analysis can give valuable information for the reconstruction of the events. Since GSR collection on persons of interest generally occurs a few minutes to hours after discharge, knowledge is needed to understand how organic (O), and inorganic (I) residues are transferred and persist. In this research, the quantities of OGSR and IGSR were assessed on the right and left hands, forearms, face, and nostrils of four shooters. Specimens were collected immediately before the discharge (shooter's blank specimens) and shortly after (30 min) using carbon adhesive stubs. Organic compounds were first extracted from the collection device and analysed using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Subsequently, IGSR particles were detected on the same stub using scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM/EDS). Shooter's blank specimen analysis revealed background contamination of both O and IGSR in the shooter's environment, predominantly attributed to the presence of an indoor shooting range. However, the background quantities generally remained below the associated 30-minute specimen. Thirty minutes after a discharge, higher quantities were generally detected on the shooter's right and left hands than on other collection regions for both GSR types. Forearms and face emerged as interesting collection alternatives, especially in cases where a person of interest may have washed their hands in the interval between the discharge and collection. In contrast, very low amounts of GSR were detected in the nostrils. Furthermore, the results indicated that OGSR and IGSR have different transfer and persistence mechanisms.

[Current approaches for sampling to study the traces of gunshot residue]

An overview of researches, mainly by foreign specialists, on current available approaches for sampling to study the traces of gunshot residue (GSR) is presented. The comparative characteristics of traditional methods of samples (use of cotton and gauze tampons, blotting paper, textile fabrics, adhesive tapes, adhesives and vacuum samplers), as well as advanced technologies, including special devices and sorbents, are given. The characteristics of samplings from hands, scalp, nostrils, clothes of examined persons as well as procedures, that allow to increase the duration of GSR detection, are described in details. The importance of GSR sustainability over time is noted. On average, the most likely detection periods of particles are less than 1 hour for samples, collected from hands, more than 1 hour for samples from clothes and 2-3 hours for face. It is possible to detect the GSR particles in hair up to 24 h., and in nasal mucus after 6 h. of shot. The methods of identification and determination for analytes of inorganic and organic nature are discussed. The most common methods for determining heavy metal particles are atomic spectrometry, namely atomic absorption with electrothermal atomization and atomic emission. The combination of scanning laser ablation and mass-spectrometry with inductively coupled plasma makes it possible to detect more than 15 analytes in a single sample. Scanning electron microscopy with X-ray detectors is effective for the examination of powder particles. The described methods of sampling complement each other increasing the possibility of evidence base for court proceedings.

The nose as a feature of forensic practice

The nose is a prominent facial structure which is too often overlooked by forensic medicine practitioners. Studies that consider the role of the nose in forensic practice are scattered throughout scientific literature. We provide a brief review of these.

Finding GSR evidence on used towels

When a firearm is discharged, gunshot residue (GSR) is produced and may be deposited on a shooter's body and his close vicinity. The tendency of GSR to drop off easily from the shooter may hinder forensic detection; this well-known phenomenon is accelerated by various common physical activities so that the number of particles detected on a suspect decreases over time. After shooting incidents, suspects will often try to cover their tracks by taking a shower. In these cases, it was assumed that no GSR will be detected upon examining the suspect's hand and hair. In the present study, we provide a way to overcome this loss of evidence by taking advantage of another occurrence, namely secondary transfer. Our participants were asked to take a shower after shooting a firearm. Samples were thereafter collected from the used bath towels and were found to contain up to a few dozen particles characteristic of GSR, including very large particles (>45 µm). The detection of GSR on a suspect's towel may provide significant forensic evidence aiding an investigation. When a shooter tries to remove evidence by taking a shower, sampling the towels that he may have used can preserve important evidence and connect a suspect to a shooting incident.

Gunshot residue detection technologies—a review

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.

Ear as an alternative sampling site for GSR analysis following shotgun discharge

Detection of GSR particles potentially indicates that a person fired a gun or somehow involved to a shooting event. GSR on the shooter's hand, face, and clothing may disappear within hours and with sweat secretion, washing or cleaning to remove evidences. Due to its anatomical properties, ears are relatively protected; therefore, we aimed to identify GSR particles on ears, to compare its anatomical parts of ears, and compare ears with common GSR sampling sites, based on firing frequency. A 12-gauge semi-automatic shotgun was used. In the 4-week study, one shot in the first week, two consecutive shots in second week, three shots in third week, and five shots in fourth week were fired by six participants. Samples were taken from MAE, CA, and AAECA of both ears and common GSR sampling sites. The characteristic 3-component structure (Pb/Sb/Ba) of the samples was analyzed by SEM/EDX. Right CA was the most suitable area for sampling, which might be attributed to posture of body during targeting. Right ear was the most suitable area to take samples from CA or MAE in 3-shot group. Besides, left AAECA in 1- and 2-shot groups and the left MAE in 5-shot group were the most suitable areas for GSR sampling. In conclusion, ear seems to be a valuable alternative for detection of GSR particles, due to its complex anatomical structure potentially preventing loss of GSR with daily cleaning. Findings suggested that crime scene investigation teams and criminal laboratory staff should consider ear as a valuable alternative for GSR detection.

Advances and limitations in the determination and assessment of gunshot residue in the environment

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.

Interpol review of gunshot residue 2016-2019

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.

Particle Analysis for the Detection of Gunshot Residue (GSR) in Nasal Samples Using Scanning Laser Ablation and Inductively Coupled Plasma-Mass Spectrometry (SLA-ICPMS)

Currently, aluminum stub with carbon adhesive devices are used to collect inorganic gunshot residues (GSR) from the hands of a shooter. In an ideal shooting case, the gunshot particles do not persist for more than 2 h in the hands of the shooter, provided that the hands have not been washed. However, for forensic analysis and inference, the extended persistence of GSR would be desirable. This study investigates a novel GSR sampling and detection protocol. Sampling was performed in the nostrils using swab devices impregnated in ethylenediaminetetraacetic acid (EDTA). The GSRs persisted for longer periods in nasal mucus than on the hands, and particles were detected 6 h after shooting occurred. The analytical determination was conducted by scanning laser ablation-inductively coupled plasma-mass spectrometry (SLA-ICPMS) which enable the identification of the number of particles and their elemental composition. Seventeen isotope signals corresponding to ¹³ C, ²⁰⁵ Tl and 15 analytes that are usually associated with the composition of GSR residues were monitored: ²⁷ Al, ²⁹ Si, ³¹ P, ³³ S, ³⁵ Cl, ³⁹ K, ⁴⁴ Ca, ⁵⁷ Fe, ⁶⁰ Ni, ⁶³ Cu, ⁶⁶ Zn, ¹¹⁸ Sn, ¹²¹ Sb, ¹³⁷ Ba, and ²⁰⁸ Pb. The SLA technique enabled the reduction of the swab analysis time to 40 min. The effectiveness of this methodology was evaluated with two types of firearms: a pistol and a shotgun. The results indicated that the methodology proposed for the analysis of the nasal GSR was effective and that it can improve or complement the forensic analyses and inferences presented in a court.