Firearm Discharge Residue Research Articles

Elemental profiling of toxic and modern primers using ICP-MS, SEM-EDS, and XPS: an application in firearm discharge residue investigation

ABSTRACT 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.

Pattern of Firearm Discharge Residue on Cotton Cloth Substrate to Determine the Range of Firing by 7.65mm Caliber of Country Made and Standard Firearm: An Original Research Study

The main purpose of the study was to collect a data related to country made and standard firearm from closerange on cotton cloth substrate to determine the range of firing, type of firearm used i.e standard or countrymade firearm as limited data are available for such lethality in india. The range of firing is very difficult toinvestigate by dispersion pattern of Gun Shot Residue in close range firing by country made pistol. Thisstudy was done to overcome that deficiency.Method- This study over a period of 3 years was carried out on live cases brought to ballistics division ofCFSL/CBI/New Delhi. Total No. of 180 samples were collected, from three different close range i.e., 4”, 8”and 12”on cotton cloth substrate. 90 samples were collected by 7.6mm country made pistol and 90 sampleswere collected by 7.65mm standard pistol.Result – Among 180 firing samples during study period, 30 firing has been done from each close range, fromstandard as well as country made pistol. The result showed the large variation in dispersion pattern of GSRfrom 4” range. At 4” distance, from country made pistol, the inner dispersion area of GSR was calculatedi.e. (7-19 cm2 app.), outer dispersion area of GSR was (30-70 cm2 app.) whereas in case of standard pistol,the inner dispersion area of GSR was (10-15 cm2app.), outer dispersion area of GSR was (40-70 cm2 app.) .Conclusions- It is found that large variation in dispersion pattern of GSR pattern has been observed, whenfiring has been done from country made pistol and standard firearm at 4” range. This study must be helpfulin estimation of exact range of firing fired from close range by 7.65mm country made pistol and standardpistol by analyzing the dispersion pattern area of Gun Shot Residue.

Single shot, single sample, single instrument detection of IGSR and OGSR using LC/MS/MS

Firearm discharge residue (FDR) contains organic and inorganic constituents that arise from the propellant; primer; and, to a lesser extent, the barrel, bullet, and casing. When a weapon is fired, residues are deposited on nearby surfaces with the hand being of primary forensic interest. Current methodology focuses on inorganic primer residues (IGSR) characterized using SEM/EDX. Advances in mass spectrometry have facilitated the detection of organic residues (OGSR) using variations of LC/MS and related ambient ionization methods. In the last few years, single sample collection has been used to characterize IGSR and OGSR via sample splitting and separate analysis by SEM and LC/MS. This paper presents an innovative approach in which IGSR and OGSR are collected on a single SEM stub sample, extracted in a two-step sequential process, and then characterized with a single instrument, LC coupled with triple quadrupole mass spectrometry. The key innovation is exploitation of host-guest and ligand chemistry to detect inorganic constituents. The precursor ion is the metal-ligand complex and the product ion is the metal cation. Identification is confirmed via isotopic ratios. A controlled shooting study using 1–3 shots from a 9mm and 0.38 revolver resulted in consistent detection of lead and EC down to a single shot discharge. Barium, calcium, and iron were also detected. The detection of antimony requires of use of tartaric acid, a multi-dentate ligand.

Firing Range Estimation of handguns (0.32 Revolver & 7.65 mm Pistol) by Studying Inorganic Constituents of Firearm Discharge Residue Particles Using Scanning Electron Microscope coupled with Energy dispersive X-rays and Atomic Absorption Spectrometer flame

Though, a number of studies regarding the analysis of firearm discharge residue (FDR) particles have been conducted globally for range estimation by utilizing cartridges of various makes and origin, but in this paper, we have conducted several firings using ammunition manufactured by Indian Ordnance Factories and studied the presence of inorganic constituents contributed by priming mixture, cartridge case and bullet for this purpose. It has been found that there is atleast one element which can be used for range estimation irrespective of its origin from priming mixture, cartridge case or bullet.

Detection of firearm discharge residue from skin swabs using trapped ion mobility spectrometry coupled to mass spectrometry

In the present work, a novel workflow for the detection of both elemental and organic constituents of the firearm discharge residue from skin swabs was developed using trapped ion mobility spectrometry coupled to mass spectrometry.

Initial evaluation of inlet thermal desorption GC–MS analysis for organic gunshot residue collected from the hands of known shooters

The discharge of a firearm produces a wealth of physical and chemical evidence. Traditional forensic analysis has focused on inorganic particulates formed from the primer, referred to as gunshot residue (GSR). The last few years have seen interest in expanding the list of target compounds to include organic constituents of firearm discharge residue (OGSR). To facilitate adoption by the forensic community, new assays ideally should exploit instrumentation commonly found in forensic laboratories such as gas chromatography/mass spectrometry (GC/MS). Here, a commercially available thermal separation probe that fits directly into the injection port was evaluated as a means of sample introduction for GC/MS operated in a selected ion monitoring mode. A statistical approach utilizing bivariate plots linked retention time to ion ratio data to afford a probabilistic interpretation of the results. A total of 27 authentic shooter swabs were collected after firing of 1–5 rounds and were analyzed in halves or triplicates. Ethyl centralite was detected in 81% of the samples; diphenylamine in 56%, and 2-nitrodiphenylamine in 14%. Dimethyl and dibutyl phthalates were detected in a majority of the swabs but also in many of the hand swab blanks. The use of surrogate standards provided a measure of recovery and reproducibility for retention times and ion ratios.

Characterization of firearm discharge residues recovered from skin swabs using sub-micrometric mass spectrometry imaging

MSI-TOF-SIMS permits the analysis of skin swabs containing GSR (or not) and OGSR without the need of sample preparation and with little to no damage to the surface of the skin swab (thus preserving the evidence for further analysis).

Evaluation and validation of ion mobility spectrometry for presumptive testing targeting the organic constituents of firearms discharge residue

Ion mobility spectrometry was evaluated and validated, using select figures of merit, for use as a presumptive test for organic constituents of firearm discharge residue collected on hand swabs.

When 'neutral' evidence still has probative value (with implications from the Barry George Case).

The likelihood ratio (LR) is a probabilistic method that has been championed as a 'simple rule' for evaluating the probative value of forensic evidence in court. Intuitively, if the LR is greater than one then the evidence supports the prosecution hypothesis; if the LR is less than one it supports the defence hypothesis, and if the LR is equal to one then the evidence favours neither (and so is considered 'neutral'-having no probative value). It can be shown by Bayes' theorem that this simple relationship only applies to pairs of hypotheses for which one is the negation of the other (i.e. to mutually exclusive and exhaustive hypotheses) and is not applicable otherwise. We show how easy it can be - even for evidence experts - to use pairs of hypotheses that they assume are mutually exclusive and exhaustive but are not, and hence to arrive at erroneous conclusions about the value of evidence using the LR. Furthermore, even when mutually exclusive and exhaustive hypotheses are used there are extreme restrictions as to what can be concluded about the probative value of evidence just from a LR. Most importantly, while the distinction between source-level hypotheses (such as defendant was/was not at the crime scene) and offence-level hypotheses (defendant is/is not guilty) is well known, it is not widely understood that a LR for evidence about the former generally has no bearing on the LR of the latter. We show for the first time (using Bayesian networks) the full impact of this problem, and conclude that it is only the LR of the offence level hypotheses that genuinely determines the probative value of the evidence. We investigate common scenarios in which evidence has a LR of one but still has significant probative value (i.e. is not neutral as is commonly assumed). As illustration we consider the ramifications of these points for the case of Barry George. The successful appeal against his conviction for the murder of Jill Dando was based primarily on the argument that the firearm discharge residue (FDR) evidence, assumed to support the prosecution hypothesis at the original trial, actually had a LR equal to one and hence was 'neutral'. However, our review of the appeal transcript shows numerous examples of the problems with the use of hypotheses identified above. We show that if one were to follow the arguments recorded in the Appeal judgement verbatim, then contrary to the Appeal conclusion, the probative value of the FDR evidence may not have been neutral as was concluded.

Preliminary evaluation of the persistence of organic gunshot residue

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.

A single approach to the recovery of DNA and firearm discharge residue evidence.

The Laboratory of the Strathclyde Police Forensic Support Department extracts DNA from cellular material recovered from garments submitted as evidence. The standard method used an adhesive tape attached to a plastic or acetate support. This paper demonstrates a method whereby a single sample, recovered from clothing, can be examined for Firearm Discharge Residue and then extracted for DNA.

Handguns and Ammunitions Indicators Extracted from the GSR Analysis

The computer automated scanning electron microscope. X-ray microanalysis of Firearms Discharge Residue (FDR) can reveal substantial information about the circumstances of their generation beyond the presence of characteristic gunshot residue (GSR). Indicators of the type of weapon and ammunition used can he obtained from the distribution of GSR particle shapes and from the multi-element analysis of the FDR sample. This is demonstrated for a large database of GSR samples from nine different handguns and over 60 different ammunitions. An example classification scheme is presented for the supporting particles generally found present in FDR. When particle type area concentration ratios are normalized to the iron (Fe) particle type, results show it is possible to distinguish much about the metal used in the weapon manufacture, whether it was of large or small caliber, whether the bullets were jacketed or plated, and whether the cartridge cases were of aluminum, brass, or nickel-plated brass. Standardization of such analytical schemes would be advantageous.

Rapid Search and Quantitative Analysis of Gunshot Residue Particles in the SEM

Automated scanning electron microscopy coupled with image analysis and X-ray micro analysis was used to characterize a variety of gunshot residue (GSR) samples. More than 500 rounds of commercially available ammunition and six different types of hand gulls were used in the study of 17 GSR and 19 reference specimens. The individual particle X-ray composition was determined for 12 different elements. Elemental composition of GSR particles was highly variable but consistent with compounds mixed into or associated with a barium oxide matrix. When present in a specimen, GSR could be adequately characterized with automated procedures in less than an hour by restricting analyses to features larger than 2 microm. In "clean" samples, a higher resolution particle search was required to avoid reporting false negatives. Careful control of the back scattered electron signal strength threshold, by reference to a standard, was needed to ensure both time-efficient and accurate analyses. Samples collected from non-shooting subjects. active in a physical environment which contained firearms discharge residue were seen to be easily contaminated by sub-micron GSR particles.

Evaluation of X-ray microfluorescence spectrometry for the elemental analysis of firearm discharge residues

The conventional technique employed to sample Firearm Discharge Residues (FDRs) is by pressing an adhesive coated SEM stub repeatedly over the area of interest. The sample is then analysed by Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX). While having excellent spatial resolution, the SEM/EDX process lacks elemental sensitivity compared to other techniques such as X-ray fluorescence (XRF), where 100× to 1000× better elemental sensitivity may be achieved. The aim of this preliminary study was to evaluate relatively new technology, X-ray microfluorescence (micro-XRF), as a method of analysing FDRs, to compare the ability of micro-XRF to screen for FDR particles on SEM stubs with that of conventional SEM/EDX analysis, and to evaluate the ability of the micro-XRF to conduct on-target FDR analysis. The micro-XRF utilises a non-destructive method that can rapidly locate and analyse individual FDR particles 10 μm in diameter and larger. This analysis has the advantage that it can produce elemental maps (by X-ray mapping) directly from the target substrates, indicating the distribution of elements across a sample. Different types of ammunition were employed to include various types of primer and bullet compositions. The projectiles and primers were fired onto various target substrates at close-range and the residues analysed by micro-XRF. SEM stubs known to contain FDR particles were also analysed by micro-XRF. The results indicate that micro-XRF can effectively detect and analyse FDR particles that are larger than 10 μm in diameter. With the present instrumental configuration (50 W tube and 100 μm collimator) the micro-XRF cannot replace the SEM/EDX for the analysis of individual FDR particles less than 10 μm in diameter. It was demonstrated that micro-XRF has significant advantages for the on-target analysis of residues resulting from close range discharges (less than 30 cm). Information obtained from the micro-XRF analysis of the bullet wipe area can also give an indication of projectile composition.

Observations and Statistics Relating to Suicide Weapons

The weapon at the scene of a suicide provides a resource in addressing such questions as frequency of blood in or on the weapon, location of the weapon with respect to the body, and evidence of firearm discharge residues on the hand. The first 195 weapons were tested for blood by a technique different from the following 202 weapons. Results were obtained which caused procedural changes in blood detection. Data are presented for frequency of blood in and on the muzzle of weapons, relative frequency of location of suicidal gunshot wound, and percent "positive" findings of gunshot residue metals on the hands. It was found that suicidal gunshot wounds were 3 times more frequent to the head than the chest, and that no significant difference was noted between males and females in this study. Scene photographs reveal that the suicide weapon is in or resting on the hand of the decedent 20% of the time with handguns and 11% of the time with long guns.

Trace analysis of explosives and firearm discharge residues in the metropolitan police forensic science laboratory

Abstract Improved methods were developed for the isolation and purification of explosives traces on handswabs. Silica capillary column gas chromatography with electron capture detection was used to analyse the cleaned-up extracts. The methods were applied to the analysis of nitroglycerine in firearm discharge residues deposited on hands and clothing by various weapons and different types of ammunition. We also describe improvements in the thin layer chromatography of nitroaromatic explosives on handswabs using an iminobispropylamine spray to form charge transfer complexes.

Characterization of firearm discharge residue of ammunition of Indian origin by neutron activation analysis

The firearm discharge residues of ammunition of Indian origin have been analysed by neutron activation analysis (NAA). Attention has been confined to the elements antimony, barium, copper and mercury. The element/element combinations detected in significant amounts in the peripheral and the outer ring regions of the bullet hole have been reported. While mercury can be added to the list of the elements usually sought for in specific cases, the interpretation of the copper values in or around the bullet hole as indicative of the use of a jacketed projectile calls for considerable caution.

Determination of lead and antimony in firearm discharge residues on hands by anodic stripping voltammetry

When a person fires a gun, trace quantities of lead, antimony and barium are deposited on the hand. Detection of high levels of these trace metals on the hand of a suspect may therefore be significant evidence in an investigation. In this study conditions for the determination of lead and antimony in gunshot residues by anodic stripping voltammetry using a mercury-coated graphite electrode are established. A sample is collected by washing the hand in 1 M hydrochloric acid. Lead is determined in a portion of this sample, with 1 M hydrochloric acid as electrolyte. Antimony is determined in a second portion, with 4 M hydrochloric acid as electrolyte. Prior separation or preconcentration steps are not required for either analysis. The procedure has been applied to samples obtained from five “normal” hands and five hands after they have fired a weapon.

Studies of the Spatial Distribution of Firearms Discharge Residues

Fingerprint lifting tape has been applied to the lifting of firearms discharge residue from various surfaces. Lifting efficiencies from coarse fabric ranged from 30 to 70%. Use of the technique has been demonstrated in identifying a bullet hole and in measuring residue patterns on floor and firing hand surfaces. In hand lifts it has been shown that autoradiography alone does not uniquely distinguish the hand of someone who has fired a revolver from the hand of someone who has not. Neutron activation analysis of lifts from selected hand areas may, however, provide such a distinction.

Time of Firing of Shot Shells

The possibility of ascertaining approximate time of firing by utilizing the phenomenon of rate of escape of gaseous products of combustion has been investigated with special reference to 12-bore, 2 1/2-in. (6.35-mm), fired cartridges made by the Indian Ordnance Factory. The relative rate of escape of gases has been determined indirectly by ascertaining the time needed to develop color in reagents by escaping gases by diazotization and coupling reaction. It has been observed that although the time to develop color tends to increase with the time lapse after firing, the observations are not interpretable for all possible time intervals due to overlapping and insignificant increase in certain intervals. A choice of suitable time intervals may be found to be useful in ascertaining the approximate time of firing, which may be determined experimentally in each case. Normal variation due to atmospheric conditions has been found not to have significant influence under certain limits. The method suggested has been found to be comparatively more useful than the already existing methods.