Associating gunpowder and residues from commercial ammunition using compositional analysis

Qualitatively identifying and quantitatively determining the additives in smokeless gunpowder to calculate a numerical propellant to stabilizer (P/S) ratio is a new approach to associate handgun-fired organic gunshot residues (OGSR) with unfired powder. In past work, the P/S values of handgun OGSR and cartridges loaded with known gunpowders were evaluated. In this study, gunpowder and residue samples were obtained from seven boxes of commercial 38 caliber ammunition with the goals of associating cartridges within a box and matching residues to unfired powders, based on the P/S value and the qualitative identity of the additives. Gunpowder samples from four of the seven boxes of ammunition could be easily differentiated. When visual comparisons of the cartridge powders were considered in addition to composition, powder samples from all seven boxes of ammunition could be reliably differentiated. Handgun OGSR was also collected and evaluated in bulk as well as for individual particles. In some cases, residues could be reliably differentiated based on P/S and additive identity. It was instructive to evaluate the composition of individual unfired gunpowder and OGSR particles. We determined that both the numerical centroid and dispersity of the P/S measurements provide information for associations and exclusions. Associating measurements from residue particles with those of residue samples collected from a test firing of the same weapon and ammunition appears to be a useful approach to account for any changes in composition that occur during the firing process.     

Is the exploding powder gas of the propellant from blank cartridges sterile?

Shots from blank weapons loaded with blank cartridges, when fired from close range or as a contact shot, almost always cause the skin to burst open and lead to injuries to structures below the surface. Subsequently, wound infections are often observed. In addition to the introduction of skin germs, the possibility exists that contaminated propellants may enter into consideration as a source of infection. Using step-by-step experimental procedures we were able to demonstrate that: 1. Blank cartridge propellants were almost always contaminated with Bacillus cereus (nitrocellulose powder more so than black powder); 2. When the shot is fired numerous bacteria survive and are forced out with the gunsmoke from the weapon and thus find their way into the wound. In principle, blank cartridge propellant thus exhibits as much potential for wound infection as the skin germs. Clearly, the species B. cereus is prominent in this context. For open injuries even with ‘harmless’ blank weapons, an antibiotic prophylaxis should always be administered.     

The influence of a possible contamination of the victim's clothing by gunpowder residue on the estimation of shooting distance

A study was conducted to assess the influence of a possible contamination of the victim's clothing by gunpowder residue on the estimation of shooting distance. The study was focused on the scenario in which the contamination might be caused by the surface on which the shot victim could fall. Contamination of two types of textile was examined after contact with two types of surfaces. One round was fired above those surfaces (the line of firing parallel to the surface) prior to the contact. It was found that few gunpowder residue particles could be transferred to the clothing. These findings should be taken into account when interpreting results for shooting distance estimation in cases when a minute quantity of gunpowder residue particles is found around the bullet entrance hole.     

The nature of the deposit of substances in gunshot injuries from a smooth-bore hunting rifle]

Direct microscopic examinations of plain-barrel hunting gun-shot wounds may reveal on the victim's skin or clothes starch or paraffin particles or impressions thereof (a secondary shell trace). These data may evidence a specific charge of the cartridge and be used to specify the distance from which the shot was made, with an obligatory experimental shot made in each case.     

Gunpowder particles as a factor in a gunshot from up close

Existence of different opinions on the role of gunpowder particles in determining close shot distance promoted the experiments with pistol "PM" and sporting fowling piece in vertical and horizontal directions at different distances from 0.5 up to 2.5 m using targets made of pasteboard and moistened photographic paper. The quantities of gunpowder particles on the targets which were calculated by stereoscopic microscope increased distinctly in vertical shot direction (from above downwards), especially at distances 2 and 2.5 m and particle flight distance rose; in horizontal shot direction distances of gunpowder particle flight didn't exceed 2-3 m.     

The determination of the distance of a shot from a smooth-bore weapon based on the damages from the action of the wad containers

Experimental shots from a No. 16 calibre single-barrelled gun using commercial cartridges in the plastic cartridge cases supplied by wad containers with Nos. 1 and 2 shots revealed that lesions that had typical morphologic structure which were characteristic of wad container action were produced at close distances (less than 2 meters). Therefore preliminary experimental shots are necessary before making concrete decisions on characteristic features of an injuring projectile and shot distance.     

Investigating the effect of changing ammunition on the composition of organic additives in gunshot residue (OGSR)

The measurement of the organic additives in smokeless gunpowder is an attractive approach for the detection of handgun use because it provides compositional information that can help associate residues and unfired gunpowder. We investigate several factors that will be required to advance the characterization of organic gunshot residue (OGSR) as a useful forensic tool, including evaluating residue contamination from previously fired ammunition, particle-to-particle compositional variability, and compositional features resulting from the type of firing primer used. Using ammunition loaded with known smokeless powders containing different stabilizers, a sequence of shots was fired from a .357 magnum revolver, and the muzzle exit residues were collected. Compositional analysis of the residues, both in bulk and as single particles, showed only a trace of the previously fired powder in the first shot and none in subsequent shots. In an additional experiment testing conventional leaded and the new lead-free firing primers, the OGSR composition was found not to depend on the primer type.     

Nanotechnology for forensic sciences: Analysis of PDMS replica of the case head of spent cartridges by optical microscopy, SEM and AFM for the ballistic identification of individual characteristic features of firearms

A novel application of replica molding to a forensic problem, viz. the accurate reproduction of the case head of gun and rifle cartridges, prior and after been shot, is presented. The fabrication of an arbitrary number of identical copies of the region hit by the firing pin and by the breech face is described. The replicas can be (i) handled without damaging the original evidence, (ii) distributed to different law enforcement agencies for comparison against other evidences found on crime scenes or ballistic tests of seized firearms, (iii) maintained on a file by the laboratories. A detailed analysis of the morphological features of the replicas has been carried out by standard microscopy techniques as well as by advanced microscopy such as scanning probe and scanning electron leading to a quantitative morphological characterization of the case heads down to the nanometer scale. The assignment of the cartridge replicas to the shooting weapon is demonstrated to hold below the micron scale, while it is hindered at the nanometer level both by the manufacturing differences and by eventual modifications occurring on the firing pin.     

Contact shot from infantry weapons with a flash-suppressor

The number of reports on contact shots from firearms with a flash suppressor attached to the muzzle is small. On the basis of a case report (suicidal shot to the forehead with a Kalschnikow AKMS 47 assault rifle) the morphological peculiarities (characteristics soot pattern, relatively small powder cavity and only minor skin tears in the presence of a bony support) are presented and the conclusions to be drawn from the findings regarding the flash-suppressor, the shot distance, the angle of the shot and the way of holding the weapon are discussed.     

六四式手枪弹壳发射顺序的研究

目的　研究六四式手枪射击弹壳的排序规律。方法　对已知顺序实弹射击取样 ,显微观察弹壳上发射过程中形成的痕迹 ,通过统计、归纳 ,从中发现与排序有关的痕迹特征 ,及其与发射顺序之间的关系。结果　研究发现 ,因子弹发射顺序不同 ,弹壳上出现的抛壳挺痕的高低 ,弹底边缘压擦痕的有无轻重 ,推弹突笋痕迹的形状位置与发射顺序有关。结论　根据抛壳挺等痕迹的具体形态 ,及变化特点 ,可判断出六四手枪弹壳的发射顺序。     

Planned complex suicide. Report of two autopsy cases of suicidal shot injury and subsequent self-immolation

Two cases of planned complex suicide are presented. In both cases, the suicidal persons shot themselves after making sure that in the sequel their bodies would be burnt. In the first case, a 65-year-old man had shot himself in the mouth and consequently fell into a fire he had lighted before. In the second case, a 43-year-old man set fire to his flat and shot himself directly afterwards. On the basis of the reported cases, a short literature review on planned complex suicides is given.     

An experimental study of powder tattooing of the skin.

Test firings were conducted on specially prepared live rabbits to determine the approximate maximum ranges at which powder tattooing occurs for different forms of gunpowder. For .38 caliber, powder tattooing from cartridges loaded with flake powder disappears at a range of 18 to 24 in. (0.4 to 0.6 m). Powder tattooing with flattened ball powder extends to 36 in. (0.9 m), while that due to ball powder extends to 48 in. (1.2m) of range. In .22 caliber, powder tattooing was observed out to 24 in. (0.6 m) with flake powder and 18 in. (0.4 m) with flattened ball. Attempts to reproduce the animal powder tattoo patterns on paper revealed that the paper patterns are consistent with skin tattoo patterns only up to 18 in (0.4 m) of range.     

Comparing the additive composition of smokeless gunpowder and its handgun-fired residues

Detecting the use of handguns via the determination of the organic additives in smokeless gunpowder residues (OGSR) presents a promising alternative to primer metal residue analysis. Compositional analysis of the gunpowder additives nitroglycerin, diphenylamine, and ethyl centralite provides information that can associate residue samples with unfired gunpowder. We evaluated the composition of seven reloading smokeless gunpowders, both in bulk and as single particles, by ultrasonic solvent extraction/capillary electrophoresis. Handgun-fired residues obtained from three common weapon calibers loaded with the known reloading powders were compared with the unfired powders. In general, the composition of the residues was similar to that found in the unfired powders. For double-base powders, comparing the ratio of the propellant (P) to the total amount of stabilizer (S) for both residue and gunpowder samples proved to be a useful measurement for identification. This P/S ratio demonstrated that the additives in the residues did not greatly change relative to the unfired powder, providing a useful indicator to aid in forensic powder and residue evaluation.     

Rapid isolation of benzodiazepines with Sep-Pak C18 cartridges

A rapid method for isolation of various benzodiazepines from human samples with Sep-Pak C18 cartridges before wide-bore capillary gas chromatography is described. The drugs dissolved in alkaline samples were directly applied to the cartridges and eluted with hexane/isopropanol (9:1). The recoveries were excellent for all drugs in urine samples, but were somewhat lower for some drugs in plasma samples. The latter problem could be easily circumvented by using a deproteinization process before their application to the cartridge. We can recommend the Sep-Pak C18 cartridges for isolation of benzodiazepines because of their simplicity and rapidity.     

Suicide,accident? The importance of the scene investigation

We present the as yet unresolved case of the death by gunshot wound of a 21-year-old student from a recent local inspection. It was reported that the daughter of the house had been shot through the window while she was washing the dishes. Slight discrepancies were noted in the statements of the family, who are very religious. The firearm, projectile and cartridge have not been found despite an intensive search. The daughter and the mother tested positive for traces of gunpowder on their hands, while in the case of the son traces were found on his hands and on his vest. That the trajectory of the projectile was from the kitchen outwards was established on the basis of a small hole in the inner pane of the kitchen window and a larger hole in the outer pane. The shot passed through the victim's cheek and the neck. The entrance wound (aditus) on the right cheek had complementary features characteristic of a gunshot from a short-barrelled firearm at relative proximity. The shot passed through the left jugular vein and the left internal carotid artery. The exit wound (exitus) was slightly larger and of irregular shape.The family chose a traditional burial. The mother and son did not present themselves for polygraph testing. A charge was filed against the mother of the deceased. Emphasis was placed on the scene investigation.A covered-up suicide? An accident (a scuffle when trying to prevent suicide)?     

The boundary ranges of the free flight of particles of gunpowder and metals in shots from a hand firearm

On the basis of equations of external ballistics and probability theory the largest possible distances of free (independent) flight of gunshot powder and metal particles having different forms and sizes were calculated. Experimental control of the calculated data for different types of battle and sports hand fire-arms was carried out. The correspondence of the calculated data to maximal free (independent) particle flight in blank shots was stated. In experiments with cartridges equipped with bullets the distances of free particle flight were significantly lesser (by 53-65%) which may be connected with effect of gunshot projectile on the process of particle distribution. Reversed adapted formulas and calculation variants are presented.     

Identification of a Suspect in a Murder Case through Recovery of Fingermarks from a Fired Cartridge Case

During the period of one year, the Police of the State of Espírito Santo in Brazil analyzed 1,431 cartridge cases obtained from crime scenes and seizures. The cartridges were subjected to a development sequence (cyanoacrylate fuming + gun bluing + fluorescent dying), and panoramic images of the developed fingermarks were generated based on the photographs taken during the rotation of the cartridges. Ridge details were observed in 50 cartridges, but only in 5 cartridges, the marks were considered with value for identification. The fingermarks were searched in the Automated Fingerprint Identification System (AFIS) of the Brazilian Federal Police and, in one case, it was possible to obtain the suspect's identification. In our knowledge, this is the first case in Brazil of identification of a suspect based on a fingermark recovered from a fired cartridge case.     

The identification of two unusual types of homemade ammunition

Illegal homemade ammunition is commonly used by criminals to commit crimes in Taiwan. Two unusual types of homemade ammunition that most closely resembling genuine ammunition are studied here. Their genuine counterparts are studied as the control samples for the purpose of comparison. Unfired ammunition is disassembled, and the morphological, dimensional, and compositional features of the bullet and cartridge case are examined. Statistical tests are employed to distinguish the dimensional differences between homemade and genuine ammunitions. Manufacturing marks on head stamps of the cartridge case are carefully examined. Compositional features of propellant powders, primer mixtures, and gunshot residues are also analyzed. The results reveal that the morphological, dimensional, and compositional features of major parts of the ammunition can be employed to differentiate homemade cartridges from genuine ones. Among these features, tool marks on the head stamps left by the bunter can be used to trace the origin of ammunition.     

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.     

Three-Dimensional Analysis of Cartridge Case Double-Casts

Due to the shot-to-shot variability in tool mark reproduction on fired cartridge cases, a method of replication is needed for the creation of training and testing sets. Double-casting is one method that has been used for this application, but the accuracy and variability of this method needs to be characterized. Three firearms were used to fire 25 cartridges each to create the master cartridge cases. The double-casting method consists of creating a silicone mold of the master cartridge case. A plastic resin mix is then poured into the mold to create the double-cast reproduction. Fifteen double-casts of each of the 75 fired cartridge cases were created across different silicone molds to analyze within- and between-mold variability. The master cartridge cases and double-casts were scanned with a confocal microscope (Sensofar® S neox) to create three-dimensional representations of the surfaces. Two similarity metrics were used for the objective comparison of the double-casts to their master cartridge cases: the areal correlation coefficient (ACCF_MAX) and the number of congruent matching cells (CMC). The ACCF_MAX and CMC data, along with visual examinations, showed that the double-casting method produces accurate reproductions. Within-mold variability was found to be minimal, and between-mold variability was low. These results illustrate that double-casting can be applied for training and testing purposes.