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.     

The Influence of Penetrative Trauma on the Rate of Decomposition*†

Abstract: An understanding of the factors affecting decomposition is important for the accurate estimation of postmortem interval. An experimental study on the influence of penetrating trauma on decomposition rate was carried out using the domestic pig, Sus scrofa. The results of this study were: (i) Diptera were preferentially attracted to and oviposited at natural orifices. Trauma sites were not preferentially selected for oviposition; (ii) no differences between trauma and non‐trauma groups were found in time to skeletonization, weight loss (p = 0.906), total body score (p = 0.824), body temperature (p = 0.967), or changes in soil pH (p = 0.684); and (iii) the effect of investigator disturbance was significant when decomposition was measured as weight loss (p = 0.000). This study suggests that penetrating trauma of the type used in this study cannot be considered a major factor in the rate of decomposition and time to skeletonization of a gunshot trauma victim.     

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.     

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.     

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.     

Gunshot residues on dry bone after decomposition-a pilot study

Abstract: Very little literature exists concerning radiochemical and microscopic analyses of gunshot wounds in decomposed material, and even less concerning skeletonized samples; the most advanced technologies may provide useful indications for the diagnosis of suspect lesions, especially if gunshot wounds are no longer recognizable. However, we know very little of the survival of gunshot residues (GSR) in skeletonized samples. This study examined nine gunshot wounds produced on pig heads which then underwent skeletonization for 4 years, and four gunshot entries on human heads from judicial cases which were then macerated to the bone in water; the samples underwent scanning electron microscopy coupled with energy dispersive X‐ray (SEM‐EDX) analysis. Positive results for GSR were observed only in four of the nine animal samples and in all four human samples. Among the human samples, two lesions showed Pb and Sb, one lesion only Pb, and one Pb, Sb, and Ba. This pilot study showed the survival of GSR in skeletal material and therefore the crucial importance of SEM‐EDX analyses on skeletonized material. Further studies are needed in order to ascertain the role of environmental modifications of GSR.     

A Rare Case of an Intact Bone Plug Associated with a Gunshot Exit Wound

This case study presents an unusual manifestation of gunshot trauma in skeletal tissue from a post‐World War II human rights abuse sample uncovered in Vilnius, Lithuania. After briefly reviewing the typical wound appearance of projectile trauma in the cranium, we discuss the presence of an intact bone plug associated with a gunshot exit wound in an individual from the Tuskulenai Case. While this individual demonstrated typical gunshot entry and exit wounds to the cranium consistent with high‐velocity trauma, the bone plug indicates that the projectile likely lost much of its kinetic energy while traveling through the cranium resulting in a low‐velocity impact at the exit site. This study reviews a similar instance of a bone plug recovered from a bioarcheological sample in Peru and emphasizes the importance of thorough archeological excavations of mass graves.     

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.     

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.     

Chemical Differentiation of Osseous and Nonosseous Materials Using Scanning Electron Microscopy–Energy-Dispersive X-Ray Spectrometry and Multivariate Statistical Analysis

Identification of osseous materials is generally established on gross anatomical features. However, highly fragmented or taphonomically altered materials may be problematic and may require chemical analysis. This research was designed to assess the use of scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM/EDX), elemental analysis, and multivariate statistical analysis (principal component analysis) for discrimination of osseous and nonosseous materials of similar chemical composition. Sixty samples consisting of osseous (human and nonhuman bone and dental) and non-osseous samples were assessed. After outliers were removed a high overall correct classification of 97.97% was achieved, with 99.86% correct classification for osseous materials. In addition, a blind study was conducted using 20 samples to assess the applicability for using this method to classify unknown materials. All of the blind study samples were correctly classified resulting in 100% correct classification, further demonstrating the efficiency of SEM/EDX and statistical analysis for differentiation of osseous and nonosseous materials.     

An Examination of the Transition of Fracture Characteristics in Long Bones from Fresh to Dry in Central Florida: Evaluating the Timing of Injury

It is important to conduct timing of injury research analyzing fracture characteristics at known postmortem intervals (PMI) because bone can retain fresh characteristics throughout the PMI. Defleshed pig (Sus scrofa) long bones were fractured weekly in two environments (full sun and shade) over 14 weeks in Central Florida and fracture characteristics were categorized (N = 136) for analysis. Results of analysis of variance (ANOVA) using time in weeks (PMI) as a dependent variable indicate significant relationships between PMI and Fracture Angle (p < 0.001), Fracture Surface (p < 0.001), and Fracture Outline (p < 0.001). Fracture characteristics associated with perimortem trauma (smooth Fracture Surfaces and curved or V‐shaped Fracture Outlines) were commonly observed. Analysis of fracture characteristics for each environment demonstrated similar patterns. Overall, the loss of only fresh fracture characteristics for each bone was noted earlier in the PMI for the Central Florida region than previously reported.     

Interpreting the Effects of Burning on Pre-incineration Saw Marks in Bone

This study examined the effects of fire on the features associated with saw marks in bone. Both class and individual characteristics were examined using stereomicroscopy and scanning electron microscopy (SEM). Twenty-four semifleshed Sus scrofa L. tibiae were sawed into three sections with the middle section having deep and shallow false starts. Twelve saw blades of varying age and type were each used to cut two tibiae. In each case, the first tibia was burned in an outdoor open fire to the point of partial calcination. The second tibia, our control, was macerated using a heated enzyme solution. Controls and burned specimens were examined for the following characteristics: breakaway spur, tooth hop, false start, exit chipping, tooth imprint, breakaway notch, pull out striae, kerf flare, and blade drift. In general, there was parity in the observed characteristics in the burned samples using the SEM and the stereomicroscope. SEM observation, however, provided enhanced images, with the addition of observing individual tooth imprints, previously not visible. Therefore, this study recommends using an SEM for the examination of saw cuts in burnt bone.     

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.     

An anthropological analysis of gunshot wounds to the chest

This analysis of gunshot trauma to the bony thorax examines 87 handgun and rifle wounds from documented cases in an effort to corroborate an earlier report and to provide the forensic community with additional literature in this area. Specifically, this study tests whether the trauma signatures associated with gunshot wounds in the bony thorax are useful in determining the direction of fire. Because the ribs occupy a significant portion of the bony thorax, they are struck more frequently than other bones and, consequently, they are the focus of this report. This study confirmed that bullets can leave distinctive markers on ribs that indicate the direction of fire, including depressed fractures, bone fragments displaced in the direction of the bullet's path, and beveling. Although forensic anthropologists can determine the direction that a bullet was traveling when it struck a given rib, they cannot give a definitive statement about the number or sequence of gunshots without supporting soft tissue evidence.     

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.     

Microscopic Pattern of Bone Fractures as an Indicator of Blast Trauma: A Pilot Study

The assessment of fractures is a key issue in forensic anthropology; however, very few studies deal with the features of fractures due to explosion in comparison with other traumatic injuries. This study focuses on fractures resulting from blast trauma and two types of blunt force trauma (manual compression and running over), applied to corpses of pigs; 163 osteons were examined within forty fractures by the transmission light microscopy. Blast lesions showed a higher percentage of fracture lines through the Haversian canal, whereas in other types of trauma, the fractures went across the inner lamellae. Significant differences between samples hit by blast energy and those runover or manually compressed were observed (p < 0.05). The frequency of pattern A is significantly higher in exploded bones than in runover and compressed. Microscopic analysis of the fracture line may provide information about the type of trauma, especially for what concerns blast trauma.     

Identification of traumatic injury in burned cranial bone: an experimental approach.

Interpreting patterns of injury in victims of fire-related deaths poses challenges for forensic investigators. Determining manner of death (accident, suicide or homicide) using charred remains is compounded by the thermal distortion and fragmentation of soft and skeletal tissues. Heat degrades thin cranial structures and obscures the characteristic signatures of perimortem ballistic, blunt, and sharp force trauma in bone, making differentiation from thermal trauma difficult. This study documents the survivability and features of traumatic injury through all stages of burning for soft tissue reduction and organic degradation of cranial bone. Forty cadaver heads were burned in environments simulating forensic fires. Progression of thermal degradation was photographically documented throughout the destructive stages for soft tissues and bone to establish expected burn sequence patterns for the head. In addition to testing intact vaults, a percentage were selectively traumatized to introduce the variables of soft tissue disruption, fractures, impact marks, and incisions throughout the cremation process. Skeletal materials were recovered, reconstructed, and correlated with photographs to discern burn patterns and survivability of traumatic features. This study produced two important results: (1) Identification of preexistent trauma is possible in reconstructed burned cranial bone. Signatures of ballistic (internal and external bevel, secondary fractures), blunt force (impact site, radiating fractures), and sharp force (incisions, stabs, sectioning) survive the cremation process. (2) In non-traumatized specimens, the skull does not explode from steam pressure but does fragment as a result of external forces (collapsed debris, extinguishment methods) and handling. The features of both results are sequentially described throughout the progression of thermal destruction.     

Identification of Bodies by Unique Serial Numbers on Implanted Medical Devices

Visual identification is the most common identification method used by medical examiners but is not always possible. Alternative methods include X‐ray, fingerprint, or DNA comparison, but these methods require additional resources. Comparison of serial numbers on implanted medical devices is a rapid and definitive method of identification. To assess the practicality of using this method, we reviewed 608 consecutive forensic autopsies performed at a regional medical examiner office. Of these, 56 cases required an alternative method of identification due to decomposition (n = 35), gunshot wound (n = 9), blunt trauma (n = 6), or charring (n = 6). Of these 56 cases, eight (14.3%) were known to have an implanted medical device. Of these eight cases, five (63%) could be positively identified by comparing serial numbers. If an implanted medical device is known to be present, and medical records are available, identification by medical device serial number should be a first‐line method.     

Identification of traumatic injury in burned cranial bone: an experimental approach.

Interpreting patterns of injury in victims of fire-related deaths poses challenges for forensic investigators. Determining manner of death (accident, suicide or homicide) using charred remains is compounded by the thermal distortion and fragmentation of soft and skeletal tissues. Heat degrades thin cranial structures and obscures the characteristic signatures of perimortem ballistic, blunt, and sharp force trauma in bone, making differentiation from thermal trauma difficult. This study documents the survivability and features of traumatic injury through all stages of burning for soft tissue reduction and organic degradation of cranial bone. Forty cadaver heads were burned in environments simulating forensic fires. Progression of thermal degradation was photographically documented throughout the destructive stages for soft tissues and bone to establish expected burn sequence patterns for the head. In addition to testing intact vaults, a percentage were selectively traumatized to introduce the variables of soft tissue disruption, fractures, impact marks, and incisions throughout the cremation process. Skeletal materials were recovered, reconstructed, and correlated with photographs to discern burn patterns and survivability of traumatic features. This study produced two important results: (1) Identification of preexistent trauma is possible in reconstructed burned cranial bone. Signatures of ballistic (internal and external bevel, secondary fractures), blunt force (impact site, radiating fractures), and sharp force (incisions, stabs, sectioning) survive the cremation process. (2) In non-traumatized specimens, the skull does not explode from steam pressure but does fragment as a result of external forces (collapsed debris, extinguishment methods) and handling. The features of both results are sequentially described throughout the progression of thermal destruction.