The "inner gunshot residue"--a gunshot entry marker in gunshot of ridged skin]

Gunshot residue below the surface of the skin is typical of a contact gunshot wound. However, in a case of our own, when a taxi-robber was shot by the cab driver through his right hand at a distance of several yards, this finding provoked quite a confusion. Only when experimental shots at thick glabrous skin were performed, it could be established that long range shots led to intraepidermal gunshot deposit too. The explanation of this phenomenon lies in the tenacity of thick skin. Unlike the thin hairy skin, which is punched out by the penetrating projectile, the thicker and more tenacious plantar/palmar epidermis gets displaced radially, the stratum germinativum tears and the projectile casts its gunshot residue in the pouch formed in such a manner. Therefore, intraepidermal gunshot residue is proof of an entrance gunshot wound but not always a sign of contact shot if the wound is located in the palmar or plantar region. It is typically produced by shots at thick skin.     

Identification of gunshot residue: a critical review

A review of the scientific papers published on inorganic gunshot residue (GSR) analysis permits to study how the particle analysis has shown its capability in detection and identification of gunshot residue. The scanning electron microscope can be the most powerful tool for forensic scientists to determine the proximity to a discharging firearm and/or the contact with a surface exposed to GSR. Particle analysis can identify individual gunshot residue particles through both morphological and elemental characteristics. When particles are detected on the collected sample, the analytical results can be interpreted following rules of a formal general interpretative system, to determine whether they come from the explosion of a primer or from other possible sources. The particles on the sample are compared with an abstract idea of "unique" GSR particle produced by the sole source of the explosion of a primer. "Uniqueness" is not the only problem related to GSR detection and identification for a forensic scientist. With "not-unique" particles interpretation of results is extremely important. The evidential strength of "not-unique" particles can increase with a more fruitful interpretative framework based on Bayes rule. For the assessment of the value of a GSR in linking a suspect and a crime, it is important to compare two hypothesis: the first can be that of the evidence if the suspect has been shooting in a specific situation, the second that of the evidence if the suspect was not involved in this shooting. This case specific or case-by-case approach is closer to what the court is interested in. The authors consider that a "case-by-case" approach should be followed whenever possible. Research of models and data such as those developed in other trace evidence material (fibres, glass, etc.) using a Bayesian approach is suggested in the interpretation of GSR.     

An unusual pattern of gunshot injury linking two homicides to the same assailant

This case report describes an unusual pattern of gunshot firing that proved useful in convicting one assailant of two murders. The assailant fired into the first victim, successively through the same entrance hole at contact range. This technique of firing twice through the same hole was also demonstrable on his second victim in the bare skull of the decomposed body. This unusual pattern noted in two homicides found two weeks apart, in concert with other circumstantial evidence, led to the successful conviction of the man for both murders.     

Unusual motor ability in gunshot injury of the heart caused by a shotgun

In a case of shotgun-injury of the heart with complete rupture of both ventricles and lesion of the aorta the victim was able to move a few metres in approximately six seconds. Despite other opinions ability to move or act can be maintained in cases of severest injuries of the heart caused by missiles with high energy.     

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.     

Survey of gunshot residue analysis in forensic science laboratories

The purpose of this survey was to determine the methods of analysis being used on gunshot residue (GSR) samples in forensic science laboratories across the United States. In addition, the two general techniques of GSR analysis are compared and contrasted. Problems encountered by analysts using scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX) are discussed.     

Analysis of gunshot residue test results in 112 suicides

The results of gunshot residue (GSR) tests in 112 suicide cases investigated by the U.S. Army Criminal Investigation Command over a ten-year period are described. Only suicide cases in which there was certainty that the victim fired a weapon were examined in an effort to reduce ambiguous results. Previous case work research by Rudzitis indicated that positive GSR test results were encountered in suicides 62% of the time using various combinations of neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS). Threshold values of 0.2-micrograms antimony and 0.3-micrograms barium (0.2-micrograms antimony and 0.5-micrograms barium after 1985) used by the U.S. Army Criminal Investigation Laboratory resulted in positive GSR results in suicide cases 38% of the time. The effects of time, location of body, handling of the body, weapon type, caliber, and condition of the hands on GSR results are examined. Case studies involving suicides by unit armorers are discussed.     

Formation of epidermal damage at entry by gunshot with a contact weapon

Examination of contact bullet wounds shows the patterned inprint of the muzzle on the skin ("stanzmark") and further ragged structures around the periphery to be the remainders of the abraded epithelium. Usually these are turned outwards and from arch-shaped intraepithelial recesses, which contain residual amounts of propellant. The damage and soiling around the point of entry are the result of two factors in combination: the combustion gases and the gases escaping between the skin surface and the front of the barrel. This leads to different amounts of skin abrasion dependent on the amount and pressure of the gases. In this way, the frequently seen difference in size and shape of the stanzmark and the muzzle front can be explained.     

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。     

A simple histochemical technique for the identification of gunshot residue

Alizarin red S (ARS) is a commonly used organic dye useful in the histologic identification of calcium deposits. ARS also forms colored reaction products with other metal ions, including barium and lead, which are present in primer residue. In histochemical studies, ARS is shown to identify primer residues from several manufacturers as well as primer residue deposited in tissue, either experimentally or in close-range gunshot wounds. This can be easily accomplished with routine histologic techniques. ARS does not stain gunpowder residue, tattoo pigment, melanin, graphite, india ink, or anthracotic pigment.     

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.     

A method for the quantitative determination of nitrites in gunshot residue cases

This paper describes a method for the quantitative determination of nitrites present in gunshot residues, using an ultraviolet-visible spectrophotometer routinely employed in colorimetric procedures. The method involves the quantitative formation of a chromophoric complex between the nitrites present in the extracted gunshot residue and the analytical reagents. The procedure has been found to be sensitive enough to detect sub-microgram quantities of nitrites in gunshot residues, and has been successfully employed in the determination of muzzle-to-target distances, a question asked often in forensic science cases.     

Firing distance estimation through the analysis of the gunshot residue deposit pattern around the bullet entrance hole by inductively coupled plasma-mass spectrometry: an experimental study

The use of inductively coupled plasma-mass spectrometry (ICP-MS) in the study of gunshot residues (GSR) is relatively recent, and only a few studies have been published on the subject. In the present paper, this instrumental technique has been used to study the deposit pattern of the GSR around the bullet entrance hole, through the analysis of antimony (Sb), barium (Ba), and lead (Pb). The data obtained were used to establish a mathematical model for estimating the firing distance. Test shots using a 6.35-mm pistol were made against a target of cotton tissue, and the amounts of Sb, Ba, and Pb deposited in quadrangular pieces of the target, cut from 4 radial positions, were determined by ICP-MS. In these experimental conditions, it was possible to estimate the firing distance on the interval [20-80] cm. The best linear correlation between ln m and d, where m is the mass of Sb, Ba, or Pb in the samples, expressed in mug/g of target tissue, and d the firing distance, was obtained at radial distances between 3.5 cm and 4.5 cm from the entrance hole. The best regression curve which adjusted to the data was a linear multiple regression between the firing distance and the logarithm of the mass of each element: d = a + b(1)X(1) + b(2)X(2) + b(3)X(3), where X(1) = ln m (Sb), X(2) = ln m(Ba) and X(3) = ln m (Pb). The accuracy of firing distance estimation using only 1 or 2 elements was not significantly different from the one obtained with the 3 elements.     

Environmental assessment of gunshot residue particles in the public domain of the United Kingdom

Only limited data currently exists on the inadvertent transfer of gunshot residue (GSR), or GSR-like particles through contact with public places. In this study, an assessment occurrence of GSR in public environments in England, UK was undertaken. Utilizing a stubbing sampling technique over 260 samples were collected from areas accessible to the public, including buses, trains, taxis, and train stations. Stub analysis was performed by Scanning Electron Microscopy with Energy Dispersive X-ray Analysis (SEM-EDX). The results showed no characteristic GSR particles were detected on any of the 262 samples taken. From these samples, a total of four indicative/consistent particles were identified on one train seat (2× BaAl, 2× PbSb). Although geographical location and firearm association is likely to influence GSR occurrence, the data suggests that the potential for inadvertent GSR transfer through contact with public transport and associated communal areas is insignificant. Further research assessing environmental background levels of GSR in additional geographical locations is critical in an evaluation of the potential for GSR transfer from the environment.     

Identification of serial homicide victims in the "Green River Murder" investigation

The Green River Murder Investigation in King County, Washington, is currently the longest and most active serial murder investigation in U.S. history. To date, little information has been reported on methods used in identification of serial murder victims. In this paper, various methods used in victim identification are reviewed and difficulties encountered during the course of the investigation are described. The experience of the authors is presented in order to acquaint other agencies with problems of victim identification associated with these serial murder victims and to provide key methods that may be useful in other such investigations.     

Homicide-suicide by a single gunshot to the head

Apart from typical suicides, there are sometimes unusual deaths from gunshots to the head. The presented case is a double death from the autopsy material of the Institute of Legal Medicine in Berlin. The report deals with a murder-suicide of a man, who killed himself and his 2-year-old daughter by a single gunshot. After having administered a tranquilizer to the child, he held her head to his own and fired a contact shot to his right temple so that the bullet passed through both heads.     

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.