Detection of Gunshot Primer Residue on Bone in an Experimental Setting—An Unexpected Finding*

Abstract: Pork ribs with intact muscle tissue were used in an experimental attempt to identify bullet wipe on bone at distances from 1 to 6 feet with 0.45 caliber, full metal jacket ammunition. This resulted in the unexpected finding of primer‐derived gunshot residue (GSR) deep within the wound tract. Of significance is the fact that the GSR was deposited on the bone, under the periosteum, after the bullet passed through a Ziploc^® bag and c. 1 inch of muscle tissue. It is also important to note that the GSR persisted on the bone after the periosteum was forcibly removed. The presence of primer‐derived GSR on bone provides the potential to differentiate gunshot trauma from blunt trauma when the bone presents an atypical gunshot wound. In this study, the presence of gunshot primer residue at a distance of 6 feet demonstrates the potential for establishing maximum gun‐to‐target distance for remote shootings.     

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.     

Primary and secondary skeletal blast trauma

This study examines primary (resulting from blast wave) and secondary (resulting from disintegrated, penetrating fragments) blast trauma to the skeleton. Eleven pigs were exposed to semi-controlled blast events of varying explosive type, charge size, and distance, including some cases with shrapnel. Skeletal trauma was found to be extensive, presenting as complex, comminuted fractures with numerous small, displaced bone splinters and fragments. Traumatic amputation of the limbs and cranium was also observed. Fractures were concentrated in areas nearer the blast, but there was generally no identifiable point of impact. Fractures were more random in appearance and widespread than those typically associated with gunshot or blunt force injury events. These patterns appear to be uniquely associated with blast trauma and may therefore assist forensic anthropologists and other forensic examiners in the interpretation of skeletal trauma by enabling them to differentiate between blast trauma and trauma resulting from some other cause.     

The Survival of Gunshot Residues in Cremated Bone: An Inductively Coupled Plasma Optical Emission Spectrometry Study

Gunshot residue (GSR) has been sought and demonstrated on many types of material and with many techniques. Inductively coupled plasma optical emission spectrometry (ICP‐OES) could be a useful method on difficult substrates, but a systematic study on burnt material has never been performed. Hence, this study aims at evaluating the usefulness and reliability of this method on burnt samples. Sixteen adult bovine ribs (eight with soft tissues, eight totally skeletonized) were shot using two kinds of projectile (both 9 mm full metal‐jacketed or unjacketed). Then, every sample was led to complete calcination in an electric oven. The area of the gunshot entrance wound was swabbed and analyzed by ICP‐OES; the results were also correlated with a previously published parallel study by scanning electron microscopy (SEM) equipped with an SEM–energy dispersive X‐ray analyzer. ICP‐OES proved to be very sensitive and reliable even on degraded material and can be an appropriate nondestructive method for detecting residues on difficult and delicate substrates such as burnt bone.     

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.     

A Molecular Method to Detect Wound Cells in Bloodstains Resultant of Sharp Force Injuries for Crime Scene Reconstruction

Previous research by the authors on an animal model showed that bloodstains can contain additional information about their somatic origin in the form of wound cells. Bloodstains produced by a gunshot wound to the head were distinguished from bloodstains produced by a gunshot wound to the chest by testing the stains for a brain microRNA marker. In this study, the effectiveness of the technique was examined on blood drops shed externally from a stab wound to the liver of rat carcasses. Specifically, investigations were conducted on the liver microRNA marker, rno‐mir‐122‐3p, with the QIAGEN miScript System, and PCR analysis. Between the two stabbing methods used, 67% of the scalpel blades and 57% of the blood drops tested positive for rno‐mir‐122‐3p; however, other samples tested negative giving inconclusive results as to the wound‐of‐origin. The amount of the liver cells in the bloodstains appeared to be related to the extent of trauma.     

Scanning Electron Microscope Analysis of Gunshot Defects to Bone: An Underutilized Source of Information on Ballistic Trauma

Recent years have seen increasing involvement by forensic anthropologists in the interpretation of skeletal trauma. With regard to ballistic injuries, there is now a large literature detailing gross features of such trauma; however, less attention has been given to microscopic characteristics. This article presents analysis of experimentally induced gunshot trauma in animal bone (Bos taurus scapulae) using full metal jacket (FMJ), soft point (SP), and captive bolt projectiles. The results were examined using scanning electron microscopy (SEM). Additional analysis was conducted on a purported parietal gunshot lesion in a human cranial specimen. A range of features was observed in these samples suggesting that fibrolamellar bone response to projectile impact is analogous to that observed in synthetic composite laminates. The results indicate that direction of bullet travel can be discerned microscopically even when it is ambiguous on gross examination. It was also possible to distinguish SP from FMJ lesions. SEM analysis is therefore recommended as a previously underexploited tool in the analysis of ballistic trauma.     

An Unusual Zip Gun Suicide—Medicolegal and Ballistic Examination

Abstract:  Home-made guns are imitations of typical firearms and usually have handgun characteristics. This article presents an unusual case of a suicide carried out by means of a fatal gunshot wound to the head using a home-made zip gun. A 49-year-old male, with a history of paranoid psychosis was found dead in the dwelling place of a family house. The investigation at the crime scene did not lead to suspicion of a gunshot wound because of the unusual nature of the firearm used. A medical examiner diagnosed an opened head injury as the primary cause of the victim's death. The autopsy findings provided immediate grounds for further inspection of the crime scene. Subsequently, a simple zip gun, which had been overlooked during the scene investigation, was discovered. An undeformed projectile recovered from the victim's head was consistent with the use of the home-made firearm. Following the completion of the investigations and autopsy, the death was classified as a suicide.     

Contribution of Antemortem Computed Tomography Findings to Cause of Death Determination: An Unusual Fatal Stroke

In the case reported here, the antemortem computed tomography scan (CT scan) was essential in the forensic investigation. A 32‐year‐old man was found fully awake with a facial abrasion, after what seemed to be a car accident. He lost consciousness suddenly one hour after initial management. Successive CT scan showed a facial fracture and a metallic foreign body in the carotid canal associated with an occlusion/dissection of the left internal carotid, a pseudoaneurysm, and a carotid‐cavernous fistula. The victim died from a stroke. Autopsy confirmed that the facial abrasion was a gunshot entrance wound, the metallic foreign body being a projectile. Intracranial vascular injuries linked with gunshot wounds are most of the time isolated and due to pelet embolism. The observed vascular injury association has never been described in the existing literature. The CT scan provided a better understanding of the chronology of events that led to death.     

An Unusual Suicide Inside a Grave with Two Gunshot Wounds to the Head—The Psychological Approach

Abstract: In this report, the authors present a case of suicide committed by a 66-year-old man, inside a grave at the local cemetery, with two gunshot wounds to the head. A multiple-paged, handwritten suicide note was found in an army type bag inside the victim’s car, while a second one was found in his house. Medicolegal examination of the body revealed two typical contact gunshot entrance wounds and one exit wound to the head. Toxicological analysis of the femoral blood was negative for alcohol and drugs. The history, scene and autopsy findings, along with further police investigation, indicated an obvious case of suicide. The literature is reviewed and discussed. We report this case as the place of suicide is extremely uncommon and as there is no mention of a gunshot suicide inside a grave in the current literature.     

The Erratic Behavior of Lesions in Burnt Bone

This study analyses depressed fractures (by blunt force trauma) and circular full‐thickness injuries (drill injuries and gunshot wounds) in charred bones. Fifty bovine ribs (total 104 lesions) were divided into three groups. The first group consisted in 20 depressed hammer‐produced fractures; in the second one, 60 round drill‐holes were produced (30 circular, 30 semicircular); in the third group, 12 fleshed and 12 skeletonized ribs were hit by 9‐mm bullets. Each specimen was carbonized in an electric oven up to 800°C. Morphological and metric analyses were performed before and after: morphological features were preserved, but depressed fractures showed an increase in their dimensions (p‐value < 0.05); the drilled holes shrunk (p‐value < 0.01); the charring cycle increased the number of fractures in samples with gunshot wounds differently in fleshed and defleshed ribs. This study showed the complex behavior of charred bone, for what concerns the interpretation of trauma and how caution should be applied.     

Frequency of bone lesions: an inadequate criterion for gunshot wound diagnosis in skeletal remains

A retrospective study was carried out on 130 fatalities due to gunshot wounds to determine whether the combined absence of bone damage and projectile in a skeleton is sufficient to eliminate a diagnosis of gunshot wound. Our findings showed that bone lesions were present in about 90% of the cases and were associated with intracorporeal projectile(s) in about 70% of the cases. The presence or absence of bone lesions seemed independent of the gun characteristics, the shot conditions, and the type of death. The cause of death was predominantly brain injury in cases with bone lesions whereas thoracic, abdominal, and peripheral vascular causes were more frequently encountered in cases without bone damage. We concluded that the combined absence of bone lesions and intracorporeal projectile (about 5% in our series) cannot exclude a diagnosis of death secondary to gunshot wounds.     

Abrasion Collar Around Shrapnel Entry Wound

Abrasion collar is usually described as a feature of bullet entry wounds caused by friction and indentation. The present case is that of the peculiar entry wound caused by a piece of flying shrapnel which was ejected from a furnace in a steel plant. The scrap metal which exploded in the plant was sourced from the West Asia region. The entry wound on the chest was circular and had an abrasion collar around it. The projectile was a cylindrical object of obscure origin. The forensic science laboratory put forth the possibility that the projectile was a component of an artillery fuze. A decades old study which employed high‐speed photography has rejected the possibility that abrasion collars are produced by friction. High‐velocity projectiles other than bullets can also produce abrasion collars as the rubbing of the bullet against the skin or its rotation are not the causative mechanisms.     

Evaluating Simulant Materials for Understanding Cranial Backspatter from a Ballistic Projectile

In cranial wounds resulting from a gunshot, the study of backspatter patterns can provide information about the actual incidents by linking material to surrounding objects. This study investigates the physics of backspatter from a high‐speed projectile impact and evaluates a range of simulant materials using impact tests. Next, we evaluate a mesh‐free method called smoothed particle hydrodynamics (SPH) to model the splashing mechanism during backspatter. The study has shown that a projectile impact causes fragmentation at the impact site, while transferring momentum to fragmented particles. The particles travel along the path of least resistance, leading to partial material movement in the reverse direction of the projectile motion causing backspatter. Medium‐density fiberboard is a better simulant for a human skull than polycarbonate, and lorica leather is a better simulant for a human skin than natural rubber. SPH is an effective numerical method for modeling the high‐speed impact fracture and fragmentations.     

A Molecular Method to Correlate Bloodstains with Wound Site for Crime Scene Reconstruction

Bloodstain pattern analysis to determine the wound‐of‐origin of bloodstains is problematic with nonspecific patterns. In this proof‐of‐concept study, the authors examined a molecular approach to correlate bloodstains with injuries using the rat as a model. Specifically, investigations were conducted on the rat brain marker, rno‐miR‐124‐3p, with the QIAGEN miScript System and real‐time PCR analysis. Rno‐miR‐124‐3p was detected in brain homogenates diluted 100,000 times; in 3‐week‐old, room temperature stored, simulated brain–blood stains; and in bloodstains from head gunshot wounds collected with swabs and subsequently frozen for 9–18 months; however, rno‐miR‐124‐3p was not detected in whole blood. Proof‐of‐principle was demonstrated by the ability to distinguish bloodstains from a gunshot wound to the head versus bloodstains from a gunshot wound to the chest, by the testing of otherwise identical bloodstains from the two patterns for the presence of the marker. The results suggest a viable approach to a longstanding problem in casework.     

The hydrodynamic effect of gunshots in cranial explosive shots

Case report on five fatal gunshot injuries in which discharge of the cranial contents had occurred owing to a skull blast. Despite an appreciable explosive action with destruction of the bony cranium, the brains were not completely destroyed. In analogy to the "Kr?nlein shot", comparative reflections were made concerning wound ballistics. The case reports show that injury patterns resembling "Kr?nlein shot" may arise in cranial blast shots in rare cases despite destroyed projectile parts and even in a mouth shot.     

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.