Computational Approach to Identify Different Injuries by Firearms

Complications arise in the analysis of gunshot wounds to the maxillofacial region, when neither the projectile nor the gun is found at the crime scene. We simulated 5‐ and 15‐cm firing distances at a human mandible to investigate the external morphology of entrance wounds based on fire range. The ammunition models, .40‐caliber S&W, .380‐caliber, and 9 × 19‐mm Luger, were constructed with free‐form NURBS surfaces. In a dynamic simulation, projectiles were fired against mandibular body 3D model at 5 and 15 cm. All entrance wounds presented oval aspect. Maximum diameter and von Mises stress values were 16.5 mm and 50.8 MPa, both for .40‐caliber S&W fired at 5 cm. The maximum energy loss was 138.4 J for .40 S&W fired at 15 cm. In conclusion, the mandible was most affected by .40‐caliber S&W and morphological differences were observable in holes caused by different incoming projectile calibers fired at different distances.     

Radiodense bullet wipe around osseous entrance gunshot wounds

“Bullet wipe” is the material deposited by a bullet on any surface with which it comes into contact after it is fired and may contain debris from the gun barrel, including particles of primer and metal fragments from previously fired bullets. X‐ray analysis is a non‐destructive method by which traces of metallic elements can be visually detected. The analysis of osseous defects for radiodense bullet wipe (RBW) assists in determining the presence or absence of perforating gunshot wounds, especially in fragmented, skeletonized remains. The aim of our current study was to determine the frequency of RBW around entrance firearms injuries that perforated bone. We prospectively analyzed entrance gunshot wounds for RBW over a three‐year period using digital X‐ray analysis (n = 59). We retrospectively reviewed the corresponding autopsy reports to determine the frequency of RBW by biologic sex, reported ancestry, age‐at‐death, location of wound, manner of death, range of fire, bullet caliber, and presence of bullet jacket. Data were analyzed by Fisher's exact test or Chi‐square test with significance levels accepted at p < 0.05. RBW was present in 66% (n = 39) of examined cases. Decedent characteristics did not significantly alter RBW distribution, including biologic sex (p = 0.75), reported ancestry (p = 0.49), and age‐at‐death (p = 0.43). Additionally, the location of the osseous entrance gunshot wound, manner of death, range of fire, and cartridge caliber did not affect RBW detection. All cases involving non‐jacketed rounds (n = 5) showed RBW (p = 0.30). To our knowledge, this study is the first to report the frequency of RBW detection from osseous entrance gunshot wounds.     

Gunshot residue patterns on skin in angled contact and near contact gunshot wounds

The goal of this study was the reproduction of shape and pattern of gunshot residues in near contact and contact gunshot wounds by a series of experimental gunshots on a skin and soft tissue model. The aim was to investigate the shape and direction of soot deposits with regard to the muzzle according to different muzzle-target angles, firing distances, type of ammunition and weapon and barrel length. Based on a review of the literature and on the results of the experiments the authors could make the following statements of gunshot residues in angled contact and close contact gunshot: (1) gunshot residues on the target surface can be differentiated in a "inner" and "outer powder soot zone"; (2) the outer powder soot zone is much less visible than the inner powder soot zone and may lack on human skin; (3) with increasing muzzle target distance both inner and outer powder soot halo increase in size and decrease in density; (4) in angled shots the inner powder soot halo shows an eccentric, elliptic shape which points towards the muzzle, regardless of ammunition, calibre and barrel length; (5) the outer powder soot points away from the muzzle in angled contact and close contact shots.     

The characteristics of head wounds inflicted by "humane killer" (captive-bolt gun)--a 15-year study

The "humane killer" or captive-bolt gun, is the tool/weapon widely used in meat industry and private farmer households for slaughtering animal stock. Out of 17,250 autopsies performed at the Institute of Forensic Medicine in Novi Sad during the 15-year period (1991-2005), 29 cases of suicides and two homicides were committed by captive-bolt pistols. Wounds inflicted by captive-bolt guns have specific morphological features, distinctive from wounds made by other kinds of hand firearms. Selected features of the captive-bolt wounds (punched round entrance and a double pattern of smoke soiling) depend on distance and angle of instrument at the time of firing. Autopsy findings were compared with an experimental model consisting of 20 domestic pigs. Obtained results confirmed that the appearance of the entrance hole and soot deposits, along with differences in shape, location, extent, and density of soot blackening, could be useful in identification of weapon, direction of discharge, shooting distance, and angle of the muzzle to the frontal and sagittal planes of the head at the moment of fire.     

Fatalities from black powder percussion handguns

Three suicides and one homicide from black powder muzzle loading handguns are reported and the muzzle velocities of two weapons are recorded. The fatal head shots caused wide wound tracts traversing the brains and intracerebral haemorrhages remote from the tract were present in every case. The skulls showed considerable fractures which were pronounced in the cases of contact shots but were also present when the range of fire was 5 m. These extensive injuries from soft lead spheres with muzzle velocities of only ∼200 m/s are attributed to the expansion of the spheres. The regularly occurring deformation resulted in 13–16 mm calibre missiles in the cases of .44 spheres. The special features of black powder such as incomplete and slow combustion resulted in intense soot deposits in the vicinity of the entrance wound and in long ranges the gunshot residues travelled. In contact shots, large pocket-like underminings even in deeper tissue layers, abundant soot along the trajectory and skin burns were observed.     

Suicide by Close-Range Gunshot Wound to the Bridge of the Nose

Suicidal gunshot wounds to the nasal bridge are rare, particularly at close range (defined as muzzle of the weapon not touching the skin surface, but near enough to deposit soot and stippling). Previously reported suicidal gunshot wounds to the nose have been through the left nostril (Forensic Sci Int 1995;71(1):25–31; J Forensic Radiol Imag 2013;1(2):63–7). The death of a 26-year-old man with a close-range gunshot wound to the bridge of the nose was deemed suicide due to history, scene, and autopsy findings. These findings included previous suicidal ideation, texted and written notes, the decedent's cross-legged position seated on the floor, the trajectory of the bullet through his head and into the ceiling fan and roof above him, and acute alcohol intoxication. This decedent may have been intending a hard contact forehead location but inadvertently fired the gun into the bridge of his nose while bending forward, prior to contact.     

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.     

9mm警用转轮手枪橡胶弹射入口的形态特征

目的观察橡胶弹射人口的形态特征,并探讨其法医学意义。方法使用9mm警用转轮手枪发射橡胶弹,在实验动物胸腹部侧面垂直射击,射击距离分别为紧密接触射击（0cm）,相对接触射击（1～6cm）,近距离射击（6-60cm）和远距离射击（60cm～有效射程25m）。92式手枪采取相同方式射击实验动物作为对照。观察射入口的形态特征,制作组织病理学切片,HE染色显微镜下观察。结果橡胶弹接触射击和近距离射击,射入口边缘整齐,有明显的擦拭轮、挫伤轮和火药斑纹;远距离射击,可见射人口边缘撕裂,挫伤轮明显增宽,皮下出血显著;与手枪弹射入口形态特征明显不同。结论9mm警用转轮手枪橡胶弹射入口典型的形态特征,可作为此类损伤的诊断指标。     

Automatic Classification of Bloodstain Patterns Caused by Gunshot and Blunt Impact at Various Distances

The forensics discipline of bloodstain pattern analysis plays an important role in crime scene analysis and reconstruction. One reconstruction question is whether the blood has been spattered via gunshot or blunt impact such as beating or stabbing. This paper proposes an automated framework to classify bloodstain spatter patterns generated under controlled conditions into either gunshot or blunt impact classes. Classification is performed using machine learning. The study is performed with 94 blood spatter patterns which are available as public data sets, designs a set of features with possible relevance to classification, and uses the random forests method to rank the most useful features and perform classification. The study shows that classification accuracy decreases with the increasing distance between the target surface collecting the stains and the blood source. Based on the data set used in this study, the model achieves 99% accuracy in classifying spatter patterns at distances of 30 cm, 93% accuracy at distances of 60 cm, and 86% accuracy at distances of 120 cm. Results with 10 additional backspatter patterns also show that the presence of muzzle gases can reduce classification accuracy.     

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.     

Effects of kinetic energy and firearm-to-target distance on fracture behavior in flat bones

This research implements a fractographic approach to investigate the relationships between kinetic energy, firearm-to-target distance, and various aspects of fracture behavior in gunshot trauma. Gunshot experiments were performed on pig scapulae (n = 30) using three firearms generating different muzzle (initial) kinetic energies, including a 0.32 pistol (103 J), 0.40 pistol (492 J), and 0.308 rifle (2275 J). Specimens were shot from two distances: 10 cm (n = 15) and 110 cm (n = 15). Features evaluated in fractographic analysis such as cone cracks, radiating cracks, crack branching points, and circumferential cracks could be easily identified and measured in flat bones and allowed for statistical comparison of crack propagation behavior under different impact conditions. Higher-energy bullets produced more radiating cracks, more crack branching points, and longer fracture lengths than lower-energy bullets. Distance had no significant effect on fracture morphology at the distances tested. That quantitative measures of crack propagation varied with energy affirms that kinetic energy transfer is important in determining the nature and extent of fracture in gunshot wounds and suggests it may be possible to infer relatively high- versus relatively low-energy transfer using these features. Ranges obtained with the three firearms exhibited considerable overlap, however, indicating that other variables such as bullet caliber, mass, and construction influence the efficiency of energy transfer from bullet to bone. Therefore, fracture morphology cannot be used to identify a specific firearm or to directly reconstruct the muzzle (initial) kinetic energy in forensic cases.     

Characteristics of Backspatter on the Firearm and Shooting Hand—An Experimental Analysis of Close‐range Gunshots

Contact and close‐range gunshot injuries can produce bloodstains on the shooting hand and weapon. In this study, backspatter was analyzed in experimental horizontal pistol shots into blood‐filled sponges. The shooting distances were set between 0 and 45 cm. With increasing shooting distance, there was a significant decrease in the degree of backspatter. Microspatter could be detected on the weapon and shooting hand up to a shooting distance of 40 cm. They were predominantly located on thumb and index finger as well as the radial dorsal aspects of the hand. Fine spray of microspatter combined with elongated droplets in the shape of exclamation marks was found at contact and 2‐cm distance shots. An angular calculation based on the shape of the bloodstains was possible up to a shooting distance of 2 cm. No bloodstains were detected beyond 45 cm.     

A Novel Application of Infrared Imaging for the Diagnosis of Death by Fire

This paper demonstrates a novel and simple technique for the diagnosis of death by fire using a digital infrared (IR) camera system. At autopsy, the inhalation of soot by a fire victim is a definite indicator proving a vital reaction during the fire. However, there can be difficulties in confirming the presence of soot because of the relative lack of soot or the similarity in color between soot and surrounding tissues. To evaluate the effectiveness of IR imaging at autopsy, we acquired internal images of the respiratory and gastrointestinal system by both an ordinary color and IR cameras. Using our method, the inhaled soot is visible as black particles or deposits, while the blood is transparent and the surrounding tissue is whitened. This technique enables the detection of normally undiscriminating soot in an ordinary color image. This is the first report suggesting the usefulness of IR imaging in forensic autopsy for the diagnosis of death by fire.     

Concordance Rate for the Identification of Distant Entrance Gunshot Wounds of the Back by Experienced Forensic Pathologists Examining Only Images of Autopsies

The images of 66 gunshot entrance wounds with a defect on the back, a bullet in the body, hemorrhage along the wound track, and logical certainty that it was an entrance wound were collected from the files of a moderately busy medical examiner's office. Participants numbering 22 board‐certified forensic pathologists viewed a single digital archival image of each of the 66 entrance wounds randomly mixed with 74 presumptive exit wounds to determine whether they were entrance or exit wounds. The concordance rate for correctly identifying the 66 logically known entrance wounds was 82.8% with a range from 58% to 97%. This pilot study was conducted to provide an evidence‐based approach to the interpretation of the direction of gunshot wounds by reviewing pathologists with access only to archival photographs, and it is not a measure of the accuracy to distinguish entrance from exit wounds when given all of the circumstances.     

Characteristics of gunshot wounds in the skull.

The analysis of trauma to the skeleton is an important aspect of forensic case work, but most pathology references devote limited attention to this topic. This paper describes various aspects of gunshot wounds, including entrance and exit patterns, angle and path, range of fire and velocity, and caliber of the bullet, based on observations of a series of known cases. Skeletal remains of 21 victims of gunshot wounds were studied. In most cases, there was documentation of the investigation, autopsy, and victim's identity. Each case was analyzed in terms of wound location, shape, size and exit/entry surface area ratio, beveling, and direction of shooting Skull entry wounds were most often round or oval. Unusual shapes were observed in bones like the mandible and mastoid process, but were also found to be triangular, nearly rectangular or irregular. Tunneling was observed in the mastoid process. The expected internal beveling was obvious in all but one skull. External beveling of an entry wound was only observed in one case (parietal bone). Exit wounds were roughly round, oval, square, and rectangular and were always more irregular than entry wounds. External beveling of exit wounds was observed in most vault bones, but there was none in the orbit, maxilla, greater wing of the sphenoid, temporal, or left occipital bone. Tangential gunshot wounds were seen in a mastoid process, zygomatic process, mandibular ramus and condyle, and occipital condyle. Most of the exit to entry surface area ratios (cm2) varied from 1.4 to 2.0. In four cases the ratio indicated that entrances were larger than exists. In conclusion, understanding of gunshot wound characteristics is an important matter to interpret distance, velocity, direction and sometimes caliber size. Assessment of this nature of gunshot wounds helps reconstruct events surrounding the death.     

Role of chemical tests and scene investigation in determination of range of fire

Forensic pathologists have historically found several characteristics of the entrance wound invaluable in determining range of fire in gunshot fatalities. Among these characteristics are the pattern and constituents of any deposited material such as soot and/or gun powder residues. We describe a case in which the application of previously described characteristics, in the absence of laboratory testing and examination of the crime scene, would have led to an erroneous conclusion with potentially grave consequences. We suggest that all attempts be made to use available laboratory tests and to perform detailed examination of crime scenes in determining the circumstances surrounding fatal gunshot injuries.     

Characteristics and Frequency of Chipping Effects in Near‐Contact Gunshot Wounds

The presence of “chipping” or “flaking” around the edges of gunshot entry wounds has been described among the characteristics of gunshot wounds in bone. In this study, the real frequency of such a peculiar feature was investigated. The presence of “chipping” was assessed on 22 gunshot wounds fired at a near‐contact range on bovine ribs with 9‐mm bullets. As controls, five samples were shot with a 3 cm range, and five from 40 cm. In 77% of cases shot at near‐contact range, a detachment of small fragments of the upper layers of bone was detected, mainly with a circumferential disposition, whereas this feature was lacking in control samples. The study demonstrated the frequency of “chipping” and that it may probably be due to a combined ballistic effect of impact of the bullet itself and expansion of gases. It may be thus considered indicative of close‐range shots.     

Postmortem Computed Tomography and Magnetic Resonance Imaging of Gunshot Wounds to the Neck

Postmortem magnetic resonance imaging (MRI) is rarely used for the radiologic assessment of gunshot injuries, although it has clear advantages over postmortem computed tomography (CT) with regard to the imaging of soft tissue injuries. Another benefit in using MRI is that lodged projectiles composed of nonferromagnetic material such as lead present only marginal metal artifacts compared with severe artifacts on CT. This case report presents CT and MRI findings in a case with two gunshot wounds to the neck: a perforating wound and a nonperforating wound with a lead bullet lodged in the cervical spine. The decedent underwent CT and MRI before the scheduled autopsy. A ring of radiopaque material under the dermis in the fatty tissue was identified at both entrance wounds on CT, which was indicative of contact shots. The perforating gunshot was clearly indicated on CT by bullet fragments along the wound channel through the perforated 6th cervical vertebra and the fractured cricoid cartilage at the exit wound. The second trajectory, however, was only assumed based on the presence of gunshot residues at the entrance wound and the position of the lodged bullet. The radiologic assessment was severely impeded by the metal artifacts on CT. Barely noticeable metal artifacts on MRI allowed for clear visualization of the soft tissue injuries and the ruptured medulla oblongata. Only MRI clarified the soft tissue injuries of the brainstem noninvasively, which could provide specific and graphic information on the rapidity of death and the incapacitation of the victim.     

The Difficulties in Assessing Wounds Created by .410 Bore Ammunition and Weapons

When interpreting firearm injuries, the distinction between gunshot wounds and shotgun wounds is important, and separation of these categories is typically straightforward. However, .410 bore firearms can make the classification difficult. Shotguns and revolvers that can fire the same .410 bore ammunition are readily available. This study investigates the soot and gunpowder deposits and pellet patterning of these two types of weapons using cartridges specially designed for .410 bore revolvers and standard birdshot pellet ammunition. For both ammunition types, the revolver had more prompt pellet dispersion and positive detection of gunpowder at greater distances compared to the shotgun. Additionally, .410 bore slugs are of similar caliber to many common bullets. In comparing the .410 bore slugs to equivalent bullets, some morphologic differences may be imparted on the skin by the slugs, but the greatest insight into the weapon remained with the retained projectiles.     

Soft tissue radiography in determining contact and near-contact gunshot wounds.

Contact and near-contact gunshot wounds ordinarily show distinctive gunpowder patterns, muzzle imprints, or tearing of the skin. Microscopic and chemical examination have been used to estimate firing distances. A new method that utilizes soft tissue radiography is described. Nonjacketed lead bullets deposit a pattern of fragments and residues in tissue circumscribing contact and close gunshot wounds. Various patterns are presented to contrast the appearance of contact from distant gunshot wounds using various firearms and different types of bullets. This procedure may be used as an adjunct in the determination of contact and close gunshot wounds.