头发对射击残留物附着的影响

利用射击残留物的存在和分布形态判断枪口与射入口的距离是现场分析的关键之一。然而我们在工作中发现,在对头部射击的案件中,弹孔周围的头发有可能对射击残留物起到屏蔽作用,尤其在贴近距离[1](2cm~5cm左右)射击的时候,绝大部分射击残留物会附着在头发而不是头皮上,本文将以实验和真实案例为基础详细说明近距离射击时头发对射击残留物附着的影响。     

Visualization of gunshot residue patterns on dark clothing

ABSTRACT: Determination of the muzzle‐to‐target distance is often a critical factor in criminal and civil investigations involving firearms. However, seeing and recording gunshot residue patterns can be difficult if the victim's clothing is dark and/or bloodstained. Trostle reported the use of infrared film for the detection of burn patterns. However, only after the film is developed are the results visible and multiple exposures at different settings may be needed. The Video Spectral Comparator^? 2000 (Foster & Freeman Ltd., Evesham, Worcestershire, U.K.) is an imaging instrument routinely used by forensic document examiners. Without use of specialized film could the VSC 2000 (at appropriate instrument settings) quickly, easily, and reliably provide instantaneous viewing, saving, and printing of gunshot residue patterns on dark and/or blood soaked clothing? At muzzle‐to‐target distances of 6, 12, and 18 in., test fires were made into five different types of dark clothing using eight different handguns of different calibers. Gunshot residues were detected for all eight calibers, and powder burn patterns were seen on dark clothing for all three target distances and calibers except 0.22 long rifle and 0.25 ACP. Bloodstains did not preclude the viewing of these patterns.     

A comparative study of gunshot residue originating from 9 mm Luger ammunition from various producers

Following previous work on differentiation between gunshot residue according to the type of ammunition used, a specific investigation was undertaken of traces originating from 9 mm Luger ammunition using SEM-EDX. The aim of this study was to determine whether GSR originating from this type of ammunition is similar, or whether differentiation could be made between particular manufacturers of Luger ammunition. The results were collected in the form of counts of particles in each of seven key elemental classes being combinations of lead, antimony and barium. These were then adjusted to a factor known as frequency of occurrence which allows comparison of the distribution of particles within the classes between samples with differences in absolute particle counts. The relationships between the samples were examined using non-parametric statistical tests: R-Spearman and tau-Kendall rank correlation coefficients. It has been found that most of the studied samples of GSR were similar to each other despite their originating from various manufacturers.     

A study of dispersion of gunshot residue from a frequently used Serbian ammunition cal. 7.65 mm to support selected aspects of casework in North Macedonia

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.     

Differentiation of bullet type based on the analysis of gunshot residue using inductively coupled plasma mass spectrometry

Porcine tissue samples shot with two different types of bullets, jacketed and nonjacketed, were collected in the fresh state and throughout moderate decomposition. Wound samples were microwave-digested and analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to detect all elements present at measurable levels in gunshot residue (GSR). Elements detected included antimony (Sb), barium (Ba), and lead (Pb), which are considered characteristic of GSR, as well as iron (Fe) and copper (Cu). These five elements were used to differentiate shot tissue and unshot tissue, as well as tissue shot by the two different bullet types, both in the fresh state and throughout moderate decomposition. The concentrations of Cu, Sb, and Pb were able to distinguish the two bullet types in fresh tissue samples at the 95% confidence level. Cu and Pb were able to differentiate the bullet types throughout moderate decomposition at the 99% confidence level.     

A method for enhancing gunshot residue patterns on dark and multicolored fabrics compared with the modified Griess test

In using infrared or infrared-enhanced photography to examine gunshot residue (GSR) on dark-colored clothing, the GSR particles are microscopically examined directly on the fabric followed by the modified Griess test (MGT) for nitrites. In conducting the MGT, the GSR is transferred to treated photographic paper for visualization. A positive reaction yields an orange color on specially treated photographic paper. The examiner also evaluates the size of the powder pattern based on the distribution of nitrite reaction sites or density. A false-positive reaction can occur using the MGT due to contaminants or dyes that produce an orange cloud reaction as well. A method for enhancing visualization of the pattern produced by burned and partially unburned powder is by treatment of the fabric with a solution of sodium hypochlorite. In order to evaluate the results of sodium hypochlorite treatment for GSR visualization, the MGT was used as a reference pattern. Enhancing GSR patterns on dark or multicolored clothing was performed by treating the fabric with an application of 5.25% solution of sodium hypochlorite. Bleaching the dyes in the fabric enhances visualization of the GSR pattern by eliminating the background color. Some dyes are not affected by sodium hypochlorite; therefore, bleaching may not enhance the GSR patterns in some fabrics. Sodium hypochlorite provides the investigator with a method for enhancing GSR patterns directly on the fabric. However, this study is not intended to act as a substitute for the MGT or Sodium Rhodizonate test.     

Development of a quantitative LC-MS/MS method for the analysis of common propellant powder stabilizers in gunshot residue

In traditional scanning electron microscopy/energy dispersive X-ray analysis of gunshot residue (GSR), one has to cope more and more frequently with limitations of this technique due to the use of lead-free ammunition or ammunition lacking heavy metals. New methods for the analysis of the organic components of common propellant powder stabilizers were developed based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). A multiple reactions monitoring scanning method was created for the screening of akardite II, ethylcentralite, diphenylamine, methylcentralite, N-nitrosodiphenylamine, 2-nitrodiphenylamine, and 4-nitrodiphenylamine, present in standards mixtures. Five out of seven of these target compounds can be selectively identified and distinguished from the two others with a high accuracy. Samples from the hands of a shooter were collected by swabbing and underwent solid phase extraction prior to analysis. Detection limits ranging from 5 to 115 mug injected were achieved. Results from several firing trials show that the LC-MS/MS method is suitable for the detection of stabilizers in samples collected following the firing of 9 mm Para ammunitions.     

Fate and Behavior of Gunshot Residue—A Review

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

Voltammetric analysis of luminescent markers in gunshot residues

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.     

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.     

92式手枪射击距离与射击残留物分布密度相关性的研究

目的研究92式手枪射击距离与射击残留物分布密度的相关性,为射击距离的推断提供依据。方法选择92式手枪,在带皮的猪肉上覆盖白色棉布,设计了0m,0．1m,0．2m,0．5m,1．0m,1．5m,3．0m,5．0m,10m,15．0m,20．0m,25．0m共12个距离进行射击,提取白棉布上的弹孔圆周和距弹孔2cm的圆周上的射击残留物,利用扫描电镜／能谱仪对不同射击距离遗留在白棉布上的射击残留物进行检验。结果白棉布上射击残留物分布密度与射击距离呈负相关的关系。结论根据棉布上射击残留物的分布密度,能够推断射击距离,对涉枪案件中射击距离的判断有一定的参考价值。     

Lead isotope measurement of primer gunshot residues and likelihood ratio predictions for forensic cartridge discrimination and individualization in China

Gunshot residues (GSR), cartridge projectiles, and casings are frequently encountered evidence in gun-related forensic investigations. However, in circumstances where the investigation of striation marks is impossible, such as unrecovered or deformed projectiles and cartridge casings, GSR deposited on the hands or clothes of the shooter and victim-related items can provide information to establish a link between the suspect, the firearms used, and the victim. Since the formula of primers used by all cartridge manufacturers in China is identical, links based on the conventional morphological and compositional analysis of GSR are difficult to establish. However, the abundance of lead isotopes in primer components of lead styphnate varies significantly, and a fundamental understanding of these differences may facilitate the validation of primer (p)GSR evidence in forensic investigations. Here, 44 pGSR samples were characterized by Pb isotope ratios of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb using laser ablation multicollector inductively coupled plasma mass spectrometry. There was no obvious mass fractionation of the lead isotope ratios of the primers from individual cartridges analyzed before and after the shooting process, thereby establishing a basis for the comparison of pGSR and unfired cartridges. Evaluation of the results using univariate likelihood ratio (LR) computations revealed low rates of misleading evidence (<0.53%) The results demonstrated that lead isotope ratio analysis of pGSR and LR predictions can provide a practicable method for forensic cartridge discrimination and individualization.     

A versatile technique for the investigation of gunshot residue patterns on fabrics and other surfaces: m-XRF

With heavy-metal-free ammunitions becoming more and more popular, it is necessary to find methods to visualize patterns of those elements in gunshot residues (GSRs) that are not accessible by chemographic coloring tests. The recently introduced millimeter-X-ray fluorescence analysis (m-XRF) spectrometer Spectro Midex M offers an easy way to record mappings of GSRs containing such elements in order to determine shooting distances as well as the general composition of these particles. A motorized stage enables samples of a maximum size of 20 x 20 cm to be investigated, like fabric, clothes, adhesive tapes (Filmolux films), and polyvinylalcohol gloves of shooter's hands. Human tissues can be measured using a Peltier-cooled specimen holder that is mounted onto the stage. As the spot size of the exiting X-rays lies in the millimeter range, which is adequate for the assessment of the residue patterns for shooting distance determination, a significant reduction in measurement time is achieved compared with mu-XRF methods. Test shots with heavy-metal-free ammunitions were performed on different target materials, like pork skin and fabric, and the elemental distributions of Ti, K, and Ga were determined. In order to show the capability of the spectrometer for conventional lead ammunitions as well, a shot series of 5-100 cm shooting distance and an adhesive tape of a shooter's hand were investigated analogously. A comparison of several methods applied in GSR investigation shows the advantages of the m-XRF method.     

False-negative probability in the SEM/EDS automated discovery of iGSR particles: A Bayesian approach

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.     

Gunshot residue in Chicago police vehicles and facilities: an empirical study

Suspects in shooting investigations in Chicago are routinely transported in department vehicles and detained in department facilities prior to gunshot residue (GSR) evidence collection. The GSR test results are used to associate the suspect with primary exposure to GSR. The potential for these vehicles and facilities being sources of secondary GSR contamination needed to be determined. A total of 201 samples were collected from randomly selected vehicles and detention facilities. The sampling collected trace materials from surfaces that suspects' hands may contact during the arrest process. These samples were examined for the presence of GSR particles using scanning electron microscopy. Upon completion of the automated analysis, those particles that met an initial GSR screening criterion were relocated and reanalyzed. The locations where GSR particles were recovered allowed us to make recommendations to the Chicago Police Department with regard to transporting and detaining these suspects. The low number of GSR particles recovered suggests that the potential for secondary contamination, although present, is relatively low.     

The judicial review of legislation in the United Kingdom: a public choice analysis

The Human Rights Act 1998 unprecedentedly enabled the senior courts in the United Kingdom to review parliamentary enactments for compatibility with the European Convention on Human Rights. This article seeks to analyze within the framework of public choice economics two phenomena arising from this development that are counterintuitive: What made Parliament voluntarily invite the judiciary to monitor its acts? Why has Parliament consistently complied with rulings of the Judicial House of Lords that challenged primary legislation over the last 10 years? It argues that the Act was designed in a way that fulfilled the electoral commitments of the enacting majority by supplying promised policies to its constituencies, while minimizing agency costs and information problems in favor of Parliament’s corporate interests. Significantly, the Act left intact the veto powers of Parliament and the European Court of Human Rights in Strasbourg. As such, it disincentivized the Judicial House of Lords to risk costly overturns of its rulings by Parliament for straying too far from the range of the ideal policy positions spanned by Parliament and Strasbourg. Drawing from the empirical evidence of the past decade, it will be shown that in nearly all cases the Law Lords have either upheld the compatibility of challenged statutes, reaffirmed parliamentary preferences, or followed the jurisprudence of the Strasbourg Court.     

A Study of the Presence of Gunshot Residue in Pittsburgh Police Stations using SEM/EDS and LC‐MS/MS

Due to possible secondary transfer of gunshot residue (GSR) onto a suspect in police custody prior to sampling, a baseline must be created for the amount of GSR present. With an increase of “lead free” ammunition, testing for both gunpowder and primer GSR is relevant. Seventy samples were collected using carbon‐coated adhesive stubs from four Pittsburgh Police Stations and vehicles to investigate these locations as sources of secondary GSR contamination. These seventy samples were analyzed for primer GSR using scanning electron microscopy‐energy‐dispersive X‐ray spectrometry. One primer GSR particle was detected; no sample was classified as positive for primer GSR. These same samples were then analyzed for gunpowder GSR using liquid chromatography coupled to tandem mass spectrometry to test for akardite II, ethylcentralite, diphenylamine, N‐nitrosodiphenylamine, 2‐nitrodiphenylamine, and 4‐nitrodiphenylamine. Ethylcentralite was quantifiable in two test samples. These results suggest there is a negligible potential for secondary transfer of primer and gunpowder GSR.     

Infectious disease surveillance in the United States and the United Kingdom: from public goods to the challenges of new technologies

Infectious diseases are a long-standing and continuing threat to health and welfare, with their containment dependent on national disease surveillance and response capacities. This article discusses infectious disease surveillance in the United States and the United Kingdom, examining historical national traditions for identifying and controlling infectious disease risks and how globalization and technical advances have influenced the evolution of their respective approaches. The two systems developed in different but parallel ways. In the United States, surveillance remained quite localized at the state level until the early twentieth century and still retains many of those features. The U.K. approach became centralized from the latter part of the nineteenth century and has principally remained so. In both cases, disease surveillance was traditionally conceived as a public good, where national or local authorities held sovereign rights and power to protect public health. With the increasing globalized nature of infectious disease, such notions shifted toward surveillance as a global public good, with countries responding in turn by creating new global health governance arrangements and regulations. However, the limitations of current surveillance systems and the strong hold of national interests place into question the provision of surveillance as a global public good. These issues are further highlighted with the introduction of new surveillance technologies, which offer opportunities for improved disease detection and identification but also create potential tensions between individual rights, corporate profit, equitable access to technology, and national and global public goods.     

Implementation and Optimization of the Sodium‐Rhodizonate Method for Chemographic Shooting Distance Estimation

In shooting incident investigations where it is important to estimate the shooting distance, the sodium‐rhodizonate coloring method has been used for the visualization of GSR patterns extensively. This publication describes the optimization of this method by the use of a heated press for the transfer of GSR traces on garments, as well as variation of a number of other important process parameters. Our final aim for this project was to prepare a formal validation of the coloring method as prerequisite for its inclusion into the scope of ISO17025‐certified methods in the GSR Laboratory. A number of important factors and process parameters were identified, such as buffer composition and pH, type of textile used as a substrate and resolution of the documentation of the results. Results were tested using a synthetic proficiency test. Our optimized method has been found to be a very effective technique for visualization of macroscopic GSR traces.