The Physical Effects of Contact and Close‐Distance Gunfire on Sweatshirt Fleece

Powder stippling caused by the impact of propellant particles during close‐distance gunfire has been previously described on skin and solid objects only. Additionally, radial tearing has been described as clear evidence of a contact‐distance shot, requiring no further testing. Patterns of discrete perforating holes (referred to here as “stippling perforations”) and other physical damage on sweatshirt fleece fabrics were prepared. Using the firearm and ammunition in this study, stippling perforations were observed to a maximum muzzle‐to‐target distance of 35 cm (10 inches). In addition, radial tearing and disintegration were present (and often more extensive) at greater than contact distance. The presence of stippling perforations could augment muzzle‐to‐target distance estimates generated using the Griess test, or allow distance estimates when the Griess test is not feasible. Unlike what has been previously reported, testing on the original evidence (or similar substitute) is warranted when physical damage is used to estimate shooting distance.     

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.     

Analyzing the Dynamics and Morphology of Cast‐off Pattern at Different Speed Levels Using High‐speed Digital Video Imaging

During a bloodstain pattern analysis, one of the essential tasks is to distinguish between different kinds of applied forces as well as to estimate their level of intensity. In this study, high‐speed digital imaging has been used to analyze the formation of cast‐off patterns generated by a simulated backswing with a blood‐bearing object. For this purpose, 0.5 mL blood was applied evenly over the last 5 cm of a blade simulant. Bloodstains were created through the controlled acceleration of a backswing at different speed levels between 1.1 m/sec and 3.8 m/sec. The flight dynamics of blood droplets were captured with an Olympus^® i‐Speed 3 high‐speed digital camera with a Nikon^® AF Nikkor 50 mm f/1.8 D lens and analyzed using the Olympus i‐Speed 3 Viewer software. The video analysis showed that, during the backswing, blood droplets would move toward the lower end of the knifepoint and would be tangentially thrown off. These droplets impacted on the horizontal surface according to the arc of the swing. An increase in velocity led to longer cast‐off patterns with distinct morphological characteristics. Under laboratory conditions, bloodstain pattern analysis allows certain conclusions about the intensity of a backswing and provides instructions on the position of the offender. However, due to the number of unknown variables at a crime scene, such interpretation of cast‐off patterns is extremely limited and should be performed with extreme caution.     

Planned Complex Occupation‐related Suicide by Captive‐bolt Gunshot and Hanging*

Abstract: Planned complex suicides are committed by using two or more previously planned methods simultaneously to make sure that death will occur even if one method fails. Herein, we presented a case of occupation‐related planned complex suicide, committed by captive‐bolt gunshot and hanging. A 29‐year‐old man, who worked as a butcher, was found dead in the stable, hanging by the neck with a captive‐bolt gun embedded in the forehead region of his head. The hanging was complete. Along the bolt canal were bone fragments, and at the end of the path was the punched‐out fragment of the skin and soft tissue. There were no fractures of the hyoid bone and laryngeal cartilages, and a superficial hemorrhage was present in the right sternocleidomastoid muscle. Our case underlines the utility of forensic autopsy and death scene investigation in reconstructing the mechanism of death, as well as the dynamics of the event.     

The Micro‐Taphonomy of Cold: Differential Microcracking in Response to Experimental Cold‐Stresses

Cold is a central feature of environments at higher latitudes and elevations. Thus, cold‐induced taphonomic changes are relevant in many forensic contexts. Fifty‐two lamb bone segments were used to assess the impact of cold, freeze‐thaw cycles, freeze‐drying, and water immersion on microstructural cracking of bone in a series of controlled exposure experiments. For each bone segment, three thin sections were examined under a light microscope. Cold exposure caused taphonomic changes in the form of microscopic cracking. Transverse cracks occurred in all treatments, whereas osteonal cracks were restricted to rapid freezing treatments. Type of cold exposure had a statistically significant effect on both the total number of cracks and each type of crack observed. Skeletal microcracking could potentially be used as a taphonomic indicator of postmortem bone exposure to sub‐zero temperatures. The type and prevalence of this damage could also be used to distinguish between different types of cold exposure.     

Detection of Gunshot Residue on Dark‐Colored Clothing Prior to Chemical Analysis

Detection of gunshot residue (GSR) is an arduous task for investigators. It is often accomplished with chemical tests, which can reveal elements and ions indicating the presence of GSR, but are likely to cause physical alteration to the pattern. In this study, the Spex Forensics Mini‐CrimeScope MCS 400, along with 16 accompanying wavelength filters, was applied to various GSR patterns and target types. Three dark shirt materials, four ammunition calibers, and eight ammunition manufacturers, along with the primer residue of the different manufacturer ammunitions were tested. Results indicate the alternate light source wavelength of 445 nm to be the optimal setting. In addition, target material plays a large role in the preservation of GSR patterns as particles burn. Furthermore, it can be extrapolated that residue, observed from a full round and firing distance of six inches, is mostly composed of unburnt gunpowder residue, not primer residue.     

Elemental Characterization and Discrimination of Nontoxic Ammunition Using Scanning Electron Microscopy with Energy Dispersive X‐Ray Analysis and Principal Components Analysis

Concerns over the toxic by‐products produced by traditional ammunition have led to an increase in popularity of nontoxic ammunition. In this work, the chemical composition of six brands of nontoxic ammunition was investigated and compared to that of a road flare, which served as an environmental source with similar composition. Five rounds of each brand were fired while a further five were disassembled and the primer alone was fired. Particles collected from all samples, including the road flare, were analyzed by scanning electron microscopy with energy dispersive X‐ray analysis. Common elements among the different ammunition brands included aluminum, potassium, silicon, calcium, and strontium. Spectra were then subjected to principal components analysis in which association of the primer to the intact ammunition sample was generally possible, with distinction among brands and from the road flare sample. Further, PCA loadings plots indicated the elements responsible for the association and discrimination observed.     

Optimization of Headspace Solid‐Phase Microextraction Technique for Extraction of Volatile Smokeless Powder Compounds in Forensic Applications

Smokeless powders are low explosives and are potentially found in cases involving firearms and improvised explosive devices. Apart from inorganic compound analysis, forensic determination of organic components of these materials appears as a promising alternative, especially the chromatographic techniques. This work describes the optimization of a solid‐phase microextraction technique using an 85 μm polyacrylate fiber followed by gas chromatography‐flame ionization detection for smokeless powder. A multivariate experimental design was performed to optimize extraction‐influencing parameters. A 2⁴ factorial first‐order design revealed that sample temperature and extraction time were the major influencing parameters. Doehlert matrix design has subsequently selected 66°C and 21 min as the compromised conditions for the two predetermined parameters. This extraction technique has successfully detected the headspace compounds of smokeless powders from different ammunition types and allowed for their differentiation. The novel technique allows more rapid sample preparation for chromatographic detection of smokeless powders.     

X‐ray Scattering Evaluation of Ultrastructural Changes in Human Dental Tissues with Thermal Treatment

Micro‐ and ultrastructural analysis of burned skeletal remains is crucial for obtaining a reliable estimation of cremation temperature. Earlier studies mainly focused on heat‐induced changes in bone tissue, while this study extends this research to human dental tissues using a novel quantitative analytical approach. Twelve tooth sections were burned at 400–900°C (30‐min exposure, increments of 100°C). Subsequent combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) experiments were performed at the Diamond Light Source synchrotron facility, where 28 scattering patterns were collected within each tooth section. In comparison with the control sample, an increase in mean crystal thickness was found in burned dentine (2.8‐fold) and enamel (1.4‐fold), however at a smaller rate than reported earlier for bone tissue (5–10.7‐fold). The results provide a structural reference for traditional X‐ray scattering methods and emphasize the need to investigate bone and dental tissues separately to obtain a reliable estimation of cremation temperature.     

Scanning Electron Microscopy–Energy‐Dispersive X‐Ray (SEM/EDX): A Rapid Diagnostic Tool to Aid the Identification of Burnt Bone and Contested Cremains

This study investigates the use of Scanning electron microscopy–energy‐dispersive X‐ray (SEM‐EDX) as a diagnostic tool for the determination of the osseous origin of samples subjected to different temperatures. Sheep (Ovis aries) ribs of two experimental groups (fleshed and defleshed) were burned at temperatures of between 100°C and 1100°C in 100°C increments and subsequently analyzed with the SEM‐EDX to determine the atomic percentage of present elements. Three‐factor ANOVA analysis showed that neither the exposure temperature, nor whether the burning occurred with or without soft tissue present had any significant influence on the bone's overall elemental makeup (p > 0.05). The Ca/P ratio remained in the osseous typical range of between 1.6 and 2.58 in all analyzed samples. This demonstrates that even faced with high temperatures, the overall gross elemental content and atomic percentage of elements in bone remain stable, creating a unique “fingerprint” for osseous material, even after exposure to extreme conditions.     

Commotio Cordis – A Report of Two Similar Cases

Commotio cordis is a rare and fatal mechano‐electric arrhythmogenic syndrome, occurring mainly during sports activities. The present study describes two similar cases of sudden death caused by commotio cordis associated with homicide. The two decedents were both 15‐year‐old male teenagers. Both collapsed within several minutes after being punched in the precordial region, as observed by witnesses at the scenes. Although electrocardiograms were not recorded at the scenes or the hospitals, the sudden onset of cardiovascular, respiratory, and neural symptoms were consistent with sudden cardiac death caused by commotio cordis. Autopsy and forensic morphology both revealed no cardiac or pericardiac structural damage, evident lesions of other internal organs, or underlying diseases, along with negative toxicological analysis, conforming to criteria for diagnosis of commotio cordis. The diagnosis of commotio cordis by forensic pathologists is important in deliberating a verdict of homicide, especially involuntary homicide. In rare instances, a death caused by commotio cordis may have a homicide manner of death.     

n‐Ethyl Pentylone‐Related Deaths in Alabama

n‐Ethyl pentylone (NEP) is a chemical substance derived from cathinone. Synthetic cathinones are an evolving group of drugs with stimulating, mind‐altering effects sometimes referred to as novel or new psychoactive substances (NPS). There is scarce information in the medical literature regarding forensic cases in which NEP is detected in toxicological testing. We present four fatalities involving NEP from Alabama in 2017. Deaths were attributed to NEP toxicity in two cases (peripheral blood concentrations of 0.121 and 0.953 mg/L) and injuries caused by gunshot wounds in two cases (peripheral blood concentrations of 0.045 and 0.031 mg/L). One case involving NEP described an individual who exhibited classic CNS‐stimulant induced erratic behavior before being found dead. These cases enhance the forensic literature regarding specific NPS like NEP and provide contextual reference for professionals considering the significance of NEP in toxicological interpretation.     

A blind trial evaluation of a crime scene methodology for deducing impact velocity and droplet size from circular bloodstains

In a previous study, mechanical engineering models were utilized to deduce impact velocity and droplet volume of circular bloodstains by measuring stain diameter and counting spines radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate the accuracy of this technique, using an applied, crime scene methodology. Calculations from bloodstains produced on paper, drywall, and wood were used to derive surface-specific equations to predict 39 unknown mock crime scene bloodstains created over a range of impact velocities (2.2-5.7 m/sec) and droplet volumes (12-45 microL). Strong correlations were found between expected and observed results, with correlation coefficients ranging between 0.83 and 0.99. The 95% confidence limit associated with predictions of impact velocity and droplet volume was calculated for paper (0.28 m/sec, 1.7 microL), drywall (0.37 m/sec, 1.7 microL), and wood (0.65 m/sec, 5.2 microL).     

The Response of Skin to Applied Stress: Investigation of Bitemark Distortion in a Cadaver Model*

Abstract: Knowledge of distortional properties of skin is important in bitemark analysis. Thus, the response of skin to stress from bites was investigated. Four sets of models were created from the dentition of one individual. Anterior teeth were systematically removed to vary contact surface area. A biting apparatus was constructed with an integrated load cell. Forty‐six bites were created perpendicular to Langer lines on six cadavers. Rate of force application and bite pressure were controlled. Metric/angular measurement and hollow volume overlays were employed. Distortion produced by each dentition was calculated and assessed. Results showed that as teeth impressed loose tissue, mesial/distal distance increased, angles of rotation flattened, and inter‐canine distance lengthened. An opposite effect was seen in tight tissue. When the surface area of the dentition was reduced, a mixture of these effects was observed. Conclusions indicated that stiffness of the tissue was the most important variable in bitemark distortion.     

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.     

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.     

Practical Considerations in Trace Element Analysis of Bone by Portable X‐ray Fluorescence

Forensic anthropologists are more often turning to nondestructive methods to assist with skeletal analyses, specifically for trace elemental analyses. Portable XRF (pXRF) instruments are versatile and are able to be used in diverse settings or for specimens of a shape and size that cannot be accommodated by laboratory‐based instruments. Use of XRF requires knowledge of analysis parameters such as X‐ray penetration and exit depth. Analysis depth was determined by examining pure elements through known thicknesses of equine bone slices. Correlation between the element's X‐ray emission energy and the depth of reading was observed. Bone surfaces from a small unknown historic cemetery were analyzed before and after sanding of the periosteal surface to observe possible changes in XRF readings based on potential diagenesis. Results validate the pXRF device as a powerful and convenient instrument for nondestructive analysis, while highlighting limitations and considerations for the analysis of osseous materials.     

Differentiation of Twenty‐One Glitter Lip‐Glosses by Pyrolysis Gas Chromatography/Mass Spectroscopy*

Abstract: Differentiation of 21 glitter lip‐glosses from seven manufacturers was attempted by pyrolysis gas chromatography/mass spectroscopy. Samples were pyrolyzed on a ribbon probe at 800°C for 20 sec and analyzed with an Agilent^® 6890N Network GC System and Agilent^® 5973 Network Mass Selective Detector with MSD Productivity ChemStation^® Data Analysis software. The total ion chromatograms obtained were examined and differences in the presence or absence of certain chromatographic peaks corresponding to certain pyrolysis products (e.g., styrene, cyclohexane) noted. In cases where the total ion chromatograms between lip‐glosses were similar, select ion profiling was performed. Of the 21 lip‐glosses, 15 were differentiated by either the total ion chromatograms alone or through select ion profiling. Considering that lip‐glosses are typically worn by young women (who are disproportionately victims of sexual assault), this study offers the potential of being able to provide investigative leads in sexual assault investigations with evidentiary samples of this kind.     

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.