The dynamic development of the muzzle imprint by contact gunshot: high-speed documentation utilizing the "skin-skull-brain model"

Many contact gunshots produce a muzzle imprint in the skin of the victim. Different mechanisms have been discussed in literature as being responsible for the creation of the muzzle imprint. Experimenting upon the synthetic non biological skin-skull-brain model, our goal was to document and study the creation of the muzzle imprint with the aid of high-speed photography. In our experiments, we could document with our high-speed photography (at exposure rates in the range of nanoseconds) the bulging, the pressing against the muzzle, and the splitting of the artificial skin. Furthermore, it was possible to photographically record the back pattern of synthetic tissue particles. And, the soot and gunpowder cavity could be reproduced experimentally. In conclusion the experiments completed with the skin-skull-brain model, using high-speed photography for documentation, show the promising possibilities of experimental ballistics with body models.     

The "skin-skull-brain model": a new instrument for the study of gunshot effects

In order to create and study wound morphology, a "skin-skull-brain model" had to be designed which would make the laboratory reproduction of a real ballistic injury possible.To simulate the human skin, an artificial skin (a silicon cap) is used. This silicon scalp contains synthetic fibers (artificial leather) to simulate the collagen and fat of the scalp. The artificial skull is a layered polyurethane sphere (19 cm o.d.; and 5, 6, or 7 mm thick) constructed in a specially designed form with a Tabula externa, Tabula interna, and a porous Diploe sandwiched in between. The periostium of the artificial skull is made of latex. This elastic latex layer prevents the bone fragments from scattering after the model has been struck by gunfire. The brain itself is simulated with ordnance gelatin, 10% at 4 degrees C, a material well known in wound ballistics. Gunshots were fired at a distance of 10 m from the model.During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real gunshot injuries.Using the "skin-skull-brain model" has some significant advantages: the model is inexpensive, easy to construct, instantly available for use, and eliminates ethics conflicts. The main advantage of such a model is, in comparison with biological substances, the high reproducibility of inflicted traumas.     

A "skin-skull-brain model" for the biomechanical reconstruction of blunt forces to the human head

In order to create and study blunt force wound morphology, a "skin-skull-brain model" had to be designed which would make the laboratory reproduction of a blunt force injury to the head possible. During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real blunt forces injuries to humans. Utilization of the "skin-skull-brain model" presents some significant advantages: the model is inexpensive, easy to construct, instantly available for use, and eliminates ethics conflicts. The main advantage of such a model is, in comparison with biological substances, the high reproducibility of experimentally inflicted traumas.     

High-speed documented experimental gunshot to a skull-brain model and radiologic virtual autopsy

The authors documented and evaluated experimental gunshots to a skull-brain model with high-speed photography and subsequent radiographic examination for comparison of the morphologic findings in the model. The artificial skull was a polyurethane ball constructed in layers, with a porous diploe sandwiched between a tabula externa and a tabula interna. The brain itself was simulated with gelatin 10% at 4 degrees C, a material well known in wound ballistics. Gunshots were fired at the model from a distance of 10 m and documented with high-speed photography (up to 50 million frames/sec). Subsequently, a complete examination of the artificial skull was performed, including spiral computed tomography (with two-dimensional and three-dimensional reconstructions) and classic skull autopsy. The high-speed photographs clearly showed the dynamic development of the skull fracture system from an external perspective. The subsequent radiographic examination of the entire head volume created two-dimensional reformations in any plane and three-dimensional reconstructions of the gunshot injury of the polyurethane skull-brain model, especially the wound channel and the fracture system. Thanks to the model and high-speed photographs, the dynamic development of the morphology of a gunshot wound could be documented and studied. The data from computed tomography, using two-dimensional and three-dimensional postprocessing with a perspective view, were very similar to those from classic head autopsy, but derived in a hands-off and nondestructive manner. This examination method leads the way to radiographic digital autopsy or virtual autopsy.     

Determined to Die! Ability to Act Following Multiple Self‐inflicted Gunshot Wounds to the Head. The Cook County Office of Medical Examiner Experience (2005–2012) and Review of Literature

Cases of multiple (considered 2+) self‐inflicted gunshot wounds are a rarity and require careful examination of the scene of occurrence; thorough consideration of the decedent's psychiatric, medical, and social histories; and accurate postmortem documentation of the gunshot wounds. We present a series of four cases of multiple self‐inflicted gunshot wounds to the head from the Cook County Medical Examiner's Office between 2005 and 2012 including the first case report of suicide involving eight gunshot wounds to the head. In addition, a review of the literature concerning multiple self‐inflicted gunshot wounds to the head is performed. The majority of reported cases document two gunshot entrance wound defects. Temporal regions are the most common affected regions (especially the right and left temples). Determining the capability to act following a gunshot wound to the head is necessary in crime scene reconstruction and in differentiation between homicide and suicide.     

利用颅骨枪弹创骨折类型推断射击方向和顺序的实验

建立利用颅骨枪弹创骨折类型推断射击方向和顺序的方法。使用国产五四式7．62mm口径手枪及五六式7．62mm口径半自动步枪,以3m的距离2次射击16具尸体的头颞部及枕部,造成颅脑贯通创,制成颅骨枪弹射入、出口各32例,并根据定位标记进行观察。结果显示：颅骨枪弹创骨折形态可分为带有斜面的孔状骨折,锁孔状骨折,放射状骨折和环状隆起骨折4种类型,其出现多见于低速枪射击,并与射击方向和顺序有直接关系。根据颅骨枪弹创骨折类型可推断射击方向和顺序。     

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.     

Tumbling abrasions. Injuries from ricocheting bullets

Atypical entrance gunshot wounds may be produced by deflected or ricocheting bullets. One special type of atypical entrance wound involves abrasion of the skin at a site that is remote from the point of dermal penetration. These remote abrasions, termed "tumbling abrasions," are produced by bullets that tumble after impact with an intermediate target. Three cases of tumbling abrasions are presented.     

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.     

A case of internal beveling with an exit gunshot wound to the skull

Exit gunshot wounds of the skull generally have external beveling while entrance wounds show internal beveling. With rare exceptions, entrance gunshot wounds show external beveling, usually of two types: the asymmetric ‘keyhole’ type and the symmetric ‘non-keyhole’ type. In exit gunshot wounds of the skull, only the keyhole type has been reported. This report shows that symmetric internal beveling from an exit gunshot wound to the skull may confuse medical personnel.     

Suicidal single gunshot injury to the head: differences in site of entrance wound and direction of the bullet path between right- and left-handed--an autopsy study

The aim of this study was to determine the differences in the anatomical site of a gunshot entrance wound and the direction of the bullet path between right- and left-handed subjects who committed a suicide by a single gunshot injury to the head. The retrospective autopsy study was performed for a 10-year period, and it included selected cases of single suicidal gunshot head injury, committed by handguns. We considered only contact or near-contact wounds. The sample included 479 deceased, with average age 47.1 ± 19.1 years (range, 12-89 years): 432 males and 47 females, with 317 right-handed, 25 left-handed, and 137 subjects with unknown dominant hand. In our observed sample, most cases involved the right temple as the site of entrance gunshot wound (about 67%), followed by the mouth (16%), forehead (7%), left temple (6%), submental (2%), and parietal region (1%). The left temple, right temple, and forehead were the sites of the gunshot entrance wounds, which were the best predictors of the handedness of the deceased (Spearman ρ = 0.149, P = 0.006). Our study showed that the direction of the bullet intracranial path in cases of suicide was even a more potent predictor of the handedness of the deceased (Spearman ρ = 0.263, P = 0.000; Wald = 149.503, P = 0.000).     

Effects of Decomposition on Gunshot Wound Characteristics: Under Moderate Temperatures with Insect Activity

Abstract:  Previous studies document characteristics of gunshot wounds shortly after they were inflicted. This study was conducted to determine if the early stages of decomposition obscure or alter the physical surface characteristics of gunshot wounds, thereby affecting the quantity and quality of information retrievable from such evidence. The study was conducted in August and September, 2005 in Nova Scotia, Canada in forested and exposed environments. Recently killed pigs were used as research models and were shot six times each at three different ranges (contact, 2.5 cm, and 1.5 m). Under these test conditions, the gunshot wounds maintained the characteristics unique to each gunshot range and changes that occurred during decomposition were not critical to the interpretation of the evidence. It was concluded that changes due to decomposition under the conditions tested would not affect the collection and interpretation of gunshot wound evidence until the skin was degraded in the late active or advanced decay stage of decomposition.     

Shored gunshot wound of exit. A phenomenon with identity crisis

Shored gunshot wound of exit is produced when the outstretched skin is impaled, sandwiched, and crushed between the outgoing bullet and the unyielding object over the exit site, thus leaving an abrasion collar on the wound margin. Proper coaptation of the wound margin is impossible because of the loss of skin just like those observed in entrance wounds. In contrast to the entrance wound, the supported exit wound shows a scalloped or punched-out abrasion collar and sharply contoured skin in between the radiating skin lacerations marginating the abrasion (Fig. 1). Should gunpowder be observed around the exit site, it is often unevenly distributed, and is not associated with searing, gunpowder stippled abrasion, tatooing, and deposition of soot.     

Bullet or bite--a contribution to the morphogenesis of gunshot dermal injury

Histopathologic studies of dermal dog bites revealed changes identical with those observed in distant gunshot skin entrance wounds and in a presternal skin stab wound made by a screwdriver. The similarity of the epithelial and collagen changes produced by these three totally different traumatizing, perforating agencies indicate that it is the bullet's penetrating and crushing power, and not its caloric content, that is responsible for the characteristic dermal collagen changes noted in these common injuries.     

External beveling of cranial gunshot entrance wounds

Entrance gunshot wounds of the skull generally have internal beveling. External beveling has been previously described in association with internal beveling (keyhole defect) and with wounds from handgun projectiles. An accidental shooting is described in which a 22-year-old male sustained a perforating gunshot wound of the head at distant range from a 5.56-mm (.223-caliber) fully jacketed rifle round. Although the entrance wound had symmetrical external beveling, misinterpretation of this particular entrance wound as an exit wound would have been difficult.     

枪弹创后置物射出口形态学的实验研究

为建立后置物射出口与射入口的检验鉴定方法，使用国产五四式7．62mm口径手枪及五六式7．62mm口径半自动步枪，以5米的距离射击约克夏种白猪18只，同时以木板、水泥板、玻璃及衣服等作为射出口衬垫物，制成后置物射出口56例，并与对照组12例射出口进行对比观察。结果表明，射出口与后置物距离在3cm以内均可出现创缘伸展轮及皮下出血，且与后置物质地及距离成正比。根据其形态分为典型及非典型两类，并建立了此类射出口的检验方法及其与射入口鉴别的依据，有助于法医在实际检验中对射击方向的判断。     

Discordance of Gross and Histologic Findings in Estimating the Range of Fire of Gunshot Wounds

Forensic pathologist use soot and/or stippling surrounding entrance gunshot wounds in categorizing range of fire. If absent, some pathologists suggest utilizing histology when the range is diagnostically critical. This study investigates the concordance of macroscopic and microscopic findings in estimating range of fire by evaluating gunshot entrance and exit wounds made through human tissue analogs at defined distances using two handgun calibers. Examination of over 150 entrance wounds verified the ease of visually detecting soot from a muzzle distance of contact to 1 foot (30.5 cm), and its absence at 9 feet (274.3 cm). Distinctly apparent was bullet wipe surrounding the entrance wounds regardless of muzzle distance. Although variations existed, dark material was histologically identified in many skin, soft tissue, and bone sections at all ranges with both calibers. These nonparallel results decrease the dependability of histology for range of fire estimation and reinforce using gross observation.     

The evaluation of a synthetic long bone structure as a substitute for human tissue in gunshot experiments

Our goal was to compare experimental gunshot wounds in our non-biological bone model with similarly created wounds in swine bones, and evaluate the results. The design of the synthetic (polyurethane) bone was patterned after human bone structure, with a compact outer layer covering a porous inner layer. Ordnance gelatin, as substitute bone marrow, was injected into the bone's hollow core. To simulate the periostium, the bone was covered with a layer of latex. Then the bone was embedded in gelatin used to simulate surrounding soft tissue. For comparison, fresh swine bones were also embedded in gelatin, and fired upon under the same guidelines. All gunshots were high-speed filmed. In our experimental study, gunshot wounds to swine bones, and to our synthetic, non-biological bones were compared. The results (the comparison between the biological swine bones and the non-biological model bones) in regard to the following points are absolutely equal: the loss of velocity and energy after striking bone, bone fragmentation, bullet deformation, and the penetrating wound channel. Continuing studies with our synthetic bone model will bring about an even greater understanding of the mechanisms of "bullet-bone interaction". For this reason, we have extended our variety of bone models to include other skeletal structures such as skull, spine, pelvis and flat bones for further gunshot experiments.