Use of scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDXA) in identification of foreign material on bullets

The authors report two cases in which examination of foreign material embedded in or adherent to bullets provided critical information in the reconstruction of a crime scene. Analysis of small particles by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) can be accomplished without destruction or injury of the particles. In one case, the detection and identification of mineral fragments embedded near the nose of a bullet provided conclusive evidence that the bullet had ricocheted from a fireplace before striking the victim. In the second case, analysis of particles from two bullets identified them as them as bone fragments, thus proving which shots fired from a police officer's gun had killed a suspected burglar. SEM-EDXA has not been widely used to identify such material on bullets, but should be considered a potentially powerful tool in forensic science.     

An evaluation of measurement uncertainty of trajectory angles using a 3D laser scanner

Measuring trajectory angles of bullet defects at a crime scene is an important part of crime scene investigation as these angles can be used for shooting incident reconstructions. The Washington State Patrol Crime Scene Response Team (WSP CSRT) had a desire to report and use measured trajectory angles. To report quantitative measurements, a statement of uncertainty for the measurement must also be reported due to an accreditation requirement through the ANSI National Accreditation Board (ANAB), through which the WSP CSRT is accredited. This evaluation examined the measurement uncertainty of the 3D laser scanning method that the WSP CSRT utilizes for measuring the vertical and azimuth angles from trajectory rods fitted to bullet defects. Three studies were performed which examined the variation of vertical and azimuth angle measurements from trajectory rods on flat surfaces, the variation of azimuth angle measurements from a trajectory rod on a curved surface, and a traceability study with known vertical and azimuth angle measurements. Seven common substrates were selected as target materials and were shot with 9 mm Luger and 0.45 Auto caliber bullets. A vehicle with one bullet defect was utilized for the curved surface study. The WSP's current fleet of Trimble X7 3D laser scanners, the WSP Criminal Investigation Division (CID) Detectives who operate these scanners, and the Forensic Scientists responsible for trajectory rod placement and angle measurements were utilized. An overall measurement uncertainty of +/− 2.6 degrees at an approximate 95% confidence interval was determined for all trajectory angles measured from trajectory rods.     

The application of lead isotope analysis to bullet individualization in two homicides.

Bullets were characterized by lead isotope ratio analysis and trace element analysis in two homicides. In one case, we concluded that a fatal bullet did not share a common origin with bullets in a box of ammunition containing 24 cartridges taken from suspects. Evidence in the second case included two bullets from the crime scene and 163 bullets taken from various suspects. We were able to infer that the two bullets from the crime scene did not share a common origin and that they differed from all of the bullets taken from suspects. All of the suspects' ammunition had been reloaded as was evident both from trace and isotopic analysis and, indeed, from visual inspection.     

Ricochet of AK bullets (7,62 × 39 mm) on concrete and cement surfaces; a forensic-based study

The ricochet behaviour of AK bullets (7,62 x 39 mm) on two different concrete samples (rough and a cement-skimmed intermediate) and one cement sample were explored in this study. The estimated critical angles for these surfaces were shown to be 10.8° and 11.1° for the rough and intermediate concrete surfaces and 13.2° for the cement surfaces. In all occasions, fragmentation of the bullets was observed upon reaching critical angles. The results from the concrete surfaces highlighted the sensitivity of AK bullet ricochet angles from concrete surfaces with a different surface roughness and composition. Almost all resulting ricochet angles for the more frangible cement surfaces were observed to be much higher than currently reported literature would suggest. Consistent bullet wipe markings were observed on most samples, acting as a strong indicator for the directionality of the projectile during ricochet. Interestingly for the cement surface, a clear relationship was reported between the angle of incidence and the depth of the crater produced. Ultimately, this study highlights the potential uncertainties and possible errors that could occur in bullet trajectory determination from ricochet marks for this bullet and target combination if theoretic interpretations alone are used. There is no substitute for bullet and surfacespecific practical trials if the most accurate shooting scene reconstructions are to be carried out.     

Trajectory Reconstruction Through Analysis of Trace Evidence in Bullet–Intermediate Target Interaction by SEM/EDX

Abstract:  A young male was shot to death by a police officer with a Chinese Type 64 7.62 mm pistol when he was dealing with an aggravated assault arising from a traffic accident. By using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), trace deposits on the discharged bullet and the intermediate target, i.e., a concrete telegraph pole at the scene, were identified to be from each other. The result demonstrated the bullet causing the death ricocheted from the concrete telegraph pole before striking the victim, thus indicating the incident was accidental. The case report illustrates the evidential value of trace materials derived, respectively, from discharged bullets and intermediate targets in bullet–intermediate target interaction for trajectory reconstruction. In addition, it indicates that the SEM/EDX method with its nondestructive nature, compared to other methods, may be more helpful in certain situations in determining the origins of trace evidentially valuable deposits on substrates.     

Multiple suicidal gunshots to the head

We report two cases of suicide by multiple gunshots to the head. The first victim (of two shots) fired the first shot, which was observed, into his mouth, leading to damage to the left optic nerve and frontal lobe. The man still was able to drive his car home, where he shot himself in his right temple. He died 2 days later. The second victim (of three shots) was a 58-year-old man who was found dead on his bed. Reconstruction of the case disclosed that the first shot had passed through his tongue and slightly damaged the second cervical vertebral body. He then shot himself in his right temple, leading to damage of the temporal lobe. Finally, he shot himself in his left temple, resulting in destruction of the pons. In the first case, an amateurishly modified 8-mm blank revolver firing 6.35-mm- (.25)-caliber ammunition was used; in the second case, a rifle firing 5.6-mm (.22)-caliber ammunition with a reduced charge was used. In both cases, low-energy transfer to brain tissue by the initial bullets was due to low bullet energy or due to the bullets' missing the brain or vital centers.     

Measurement of kinetic energy dissipation with gelatine fissure formation with special reference to gelatine validation

Various methods for calculating the amount of kinetic energy dissipated by a bullet into ballistic gelatine have been suggested in literature. These methods were compared using the results of thirteen 9 mmx19 mm pistol and five 7.62 mmx 39 mm rifle bullets shot into 10% ballistic gelatine. The Wound Profile Method gave the highest correlation, 0.89, with the measured amounts of dissipated kinetic energy. The Fissure surface area and total crack length method gained 0.51 and 0.52, respectively. The experimental results were also compared with those from pig tests with the same bullet types. Using the z-test at 95% level of confidence no difference between impact velocity normalized bullet decelerations could be determined for the 9 mm bullet used. The same test showed significant difference for 7.62 mm bullets. That, however, can be considered to be the result of the bullet's tendency to tumble in non-homogenous living tissue causing significant dispersion of observed deceleration values. The results add further evidence supporting the validity of 10% gelatine at +4 degrees C as wound ballistic tissue simulant. The study also introduces the use of an elastic "shroud" to hold the gelatine in place, to some extent reduce the effects of asymmetric expansion of the gelatine and to simulate the expansion suppression effect of surrounding tissues.     

Bullet Caliber and Type Categorization from Gunshot Wounds in Sus Scrofa (Linnaeus) Long Bone

Studies on ballistic trauma to the ribs and thorax, cranium, and long bones demonstrate the potential of obtaining a bullet caliber from an entrance wound. In order to validate prior research on caliber estimation in bone tissue and assess the viability of bullet type determination based on the macroscopic evidence at the entrance wound, thirty fleshed pork (Sus scrofa) shoulders (humeri) were shot with either lead or copper jacketed bullets in one of three calibers; 0.22, 9 mm, or 0.38. Overall, our findings are consistent with previous research indicating that calibers can be grouped into “small” and “large” categories. Bullet type, lead or copper jacket, can be ascertained based on cortical flaking and the analysis of materials deposited around the entry wound. The addition of this evidence holds value in cases where no firearm or ballistic evidence is recovered from a crime scene.     

七七式手枪弹头发射顺序的规律性研究

目的研究总结七七式手枪射击弹头的排序。方法对已知顺序的实弹射击取样,显微观察弹头上连续射击过程中形成的痕迹,通过统计、归纳,从中发现各痕迹与射击顺序之间的关系。结果根据弹头上的磕碰痕迹、顶压痕迹的出现规律判断出七七式手枪发射子弹的顺序。     

Utilization of X‐ray Computed Tomography for the Exclusion of a Specific Caliber and Bullet Type in a Living Shooting Victim

A bystander claimed to have been shot by a police officer, and CT scans were used to match qualitative and quantitative aspects of the unremoved bullet with police issued 9 mm Luger ammunition. CT scan methodology proved a valid approach for the measurement of bullets based on calculated measurement capability and correlation with “gold standard” physical measurement by vernier caliper. Measurements regarding length and base diameter, as well as length/diameter ratio, were insufficient to unambiguously identify a specific caliber, or a bullet of specific mass within a caliber class. It was, however, possible to exclude a bullet of specific design and mass with well‐characterized precision and accuracy values under selected CT scan conditions. A 9 mm Luger bullet (115 gr FMJ RN) was excluded from involvement in a shooting based on qualitative bullet shape combined with length, base, and ratio measurements of the bullet in‐situ for the victim.     

Behavior of expelled glass fragments during projectile penetration and perforation of glass

Bullets striking common forms of flat glass with an orthogonal intercept angle result in a cloud of ejected glass fragments that are in concert with the exiting bullet's flight path. This is not the case with strikes at angles other than orthogonal. In these situations, the expelled glass fragments follow a very different course from that of the exiting projectile. This is both counterintuitive and a potential source of serious error in the evaluation and reconstruction of a shooting victim's position and orientation at the moment the victim was struck by a bullet that has passed through a nearby source of glass such as a vehicle side window or a window in a building. The flight path of the ejected glass fragments is, however, predictable and is dictated by the orientation of the plane of the glass opposite the projectile's impact site.In all cases, these expelled glass particles have considerable velocity and can produce pseudostippling of the skin in individuals located downrange of bullet-struck glass and near the projectile's exit site. The distribution and location of such pseudostippling and its relationship to the associated bullet hole in glass have important reconstructive value. A proper and reliable reconstruction of the victim's position in such cases will require the integration of scene information with the autopsy findings.     

Faux Blood Fingermark on Pistol: Latent Fingerprint Developed by Whole Blood

We present a case of a faux blood fingermark, wherein a natural latent fingerprint on the pistol at the crime scene was enhanced by the whole blood of the victim. A male was shot to death. The crime scene investigator did not find any blood fingermark during the collection of evidence, but a blood fingerprint was noticed in the firearms examination. We identified that the fingerprint was of the victim; a series of experiments on the nonporous substrate were then conducted; the death in this case was classified as a suicide. The phenomenon is interesting, and thus, calls for attention of the forensic community.     

The effect of the THV bullet in animal tissue

The Très Haute Vitesse (THV) bullet was introduced to meet the requirements of law enforcement officers, as an alternative to larger calibre fully jacketed bullets, since expanding or exploding bullets are not relevant in Europe. To examine the effect of the THV bullet in tissue, especially the size of the lesion and the degree of overpenetration, 11 recently killed pigs were shot with the weapons used by the Danish Police Force and a 9-mm pistol for reference. The ammunition was THV in the calibres 7.65 mm, 0.38, and 9 mm, using conventional fully jacketed bullets for comparison. The lesions were considerably larger when the THV bullet was used, the entry wound in particular, being roughly twice the diameter in the case of the THV bullet as compared to the fully jacketed bullet of similar calibre. Only one 7.65-mm THV bullet overpenetrated the target when fired against the thorax or abdomen of the pigs and then with only minimal residual energy. All fully jacketed 7.65-mm bullets, all 0.38 bullets, with the exception of one THV bullet, and all 9-mm bullets overpenetrated the target. The 7.65-mm THV bullet produced a lesion which in its extent resembled that of the fully jacketed 9-mm bullet, and should be a suitable alternative for the Danish Police Force.     

A Ballistics Examination of Firearm Injuries Involving Breast Implants

This ballistics study examines whether saline breast implants can decrease tissue penetration in firearm injuries. We hypothesize that the fluid column within a saline breast implant can alter bullet velocity and/or bullet pattern of mushrooming. The two experimental groups included saline implants with 7.4 cm projection and a no implant group. The experimental design allowed the bullet to pass‐through an implant and into ballistics gel (n = 10) or into ballistics gel without passage through an implant (n = 11). Shots that passed through an implant had 20.6% decreased penetration distance when compared to shots that did not pass‐through an implant; this difference was statistically significant (31.9 cm vs. 40.2 cm, p < 0.001). Implant group bullets mushroomed prior to gel entry, but the no implant group mushroomed within the gel. Bullet passage through a saline breast implant results in direct bullet velocity reduction and earlier bullet mushrooming; this causes significantly decreased ballistics gel penetration.     

Ricochet Behavior on Glass—Critical Ricochet Angles,Ricochet Angles,and Deflection Angles

For shooting scene reconstruction purposes, knowledge about the ricochet behavior of bullets provides valuable information. In this study, the critical ricochet angles of four cartridge types were established on plain float glass. The estimates of the critical ricochet angles varied between cartridge types and were 21.0° for .32 Auto FMJ bullets, 15.8° for 9 mm Luger FMJ bullets, 17.6° for .45 Auto FMJ bullets, and 21.3° for 9 mm Luger, Action NP bullets. The corresponding ricochet and deflection angles per incidence angle varied depending on the state of the ricocheted bullets. The mean ricochet angles are always lower than the corresponding angles of incidence, and the mean ricochet angles for the FMJ bullets with undamaged jackets are lower than those of bullets where the jacket is either damaged or the bullet partially ricocheted and partially perforated. Mean ricochet angles are lower for undamaged FMJ bullets than for undamaged Action NP bullets.     

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.     

A metallurgical review of the interpretation of bullet lead compositional analysis

Comparison of the minor and trace element compositions of bullet lead alloys has been used by some forensic examiners to make definitive positive associations between bullets or lead fragments at a crime scene and samples of bullets linked to a suspect(s). Such conclusions have been based on the elemental analysis of isolated groups of bullets with no consideration of the metallurgical processes involved in the production and refining of the bullet lead alloys. An understanding of the metallurgy of lead refining reveals that the elements quantified in the forensic analysis are carefully controlled in the refining process and that there are logical reasons why some elements are more discriminatory than others. Data for lead alloys supplied to two major ammunition manufacturers confirm that multiple indistinguishable shipments of lead alloys from secondary lead refiners to the ammunition manufacturers are made each year and over a period of many years. The data also demonstrate that distinguishable compositions can come from the same melt or "source" of lead alloy. These results clearly indicate that bullets with indistinguishable compositions could have come from different lead "sources" produced in the same or different years. Furthermore, the observation that two bullets have a distinguishable composition does not necessarily mean that they came from a different "source".Our results show that the forensic examiner using a method of bullet lead alloy elemental analysis, which quantifies up to six elements is restricted to concluding only that indistinguishable bullets might have come from the same "source," not that they did come from the same "source". In addition, it is quite possible that multiple bullets with similar but distinguishable compositions could have come from the same "source". The authors therefore feel that there is no scientific validity to any conclusions more positive than attributing the possible association as to molten source among bullets from different samples. An understanding of the metallurgical principles operative in the melting/casting process as well as the data acquired for this study, indicate that any forensic conclusions which associate unknown bullets with the "same source", and/or "same box" should fail most or all Daubert criteria.     

An unsuccessful murder

The victim of an attempted murder, who was shot in the head by her husband, survived when the bullet failed to penetrate her skull, apparently because he had scored the bullet twice across its nose and used an outdated power charge. The husband succeeded in killing himself with a second shot.     

Detection of bone and bone-plus-bullet particles in backspatter from close-range shots to heads.

A victim was shot in the head with a 9-mm Smith & Wesson pistol using Winchester Silvertip hollow-point ammunition. Of interest in this case was the distance from the muzzle of the weapon to the victim's head, since the wound characteristics were equivocal for firing distance. Two other handguns (revolvers) were involved in this shooting, in addition to a revolver owned by the victim. The handguns were sampled using tape lifts, and the casings were sampled by washing them in distilled water, followed by vacuum filtration of the washing water through 0.2-microns-pore Nuclepore filters. These materials were examined by scanning electron microscopy/energy-dispersive X-ray analysis. Calcium-phosphorous (bone) particles were detected on the 9-mm Smith & Wesson pistol, on two casings found at the scene, and on one of the revolvers. Two of the calcium-phosphorous particles on the casings had associated bullet fragments. Test shots on live pigs destined for slaughter showed that bone particles are a feature of backspatter from close-range shots to heads. Contamination of nearby surfaces by bone fragments and bone-plus-bullet fragments, as well as other organic debris, appears to be quite heavy.