Assets and pitfalls of chemical and microscopic analyses on gunshot residues in skeletonized bodies: a report of five cases

Investigating gunshot wounds in charred bone with XRF spectroscopy: a technical note

The analysis of traces of injuries can be difficult in cases of charred human remains since the alteration and fragmentation are high. The aim of this study is to explore the use of X-Ray Fluorescence (XRF) technique as a screening tool for detecting and analyzing gunshot residues (GSR) on cremated and highly fragmented materials, as it is a technique that allows for fast qualitative investigations without altering the sample or requiring sample preparation. The study was carried out on two steps: firstly, on completed skeletonized bones to verify if GSR survive to burning; secondly, we considered a more realistic situation, in which soft tissues were present before the shooting. To this aim, nine adult bovine ribs, four retaining soft tissue, five completely skeletonized, were subjected to a shooting test using two types of 9 mm projectiles (jacketed and unjacketed bullets). The ribs were then burnt until complete calcination in an electric furnace. The entry wound of each rib was analyzed using XRF, revealing traces of GSR. The XRF analysis showed that all samples, except for one, contain Pb and/or Sb near the lesion. Furthermore, the samples hit by unjacketed bullets had a more significant presence of Pb in macroscopic yellow areas, which persisted when moving away from the gunshot. These findings could pave the way for the use of XRF technology, mostly when a fast and immediate scan must be done on osteologic materials by a conservative method.

Burning temperature and bone modification: The cremation dynamics

Burning a body is one of the best-known methods to conceal a crime. The aim of this study is to identify thermal changes in bones burned at pre-set temperatures. 100 cadavers undergone cremation were analysed. Cremation temperatures ranged from 600 to 1200 °C, whereas cremation time was monitored. Morphological and colour changes of the bones, the development of fire-related fractures and surface were studied to analyse bone response to thermal alteration.

A scanning electron microscopy study of projectile entry fractures in cortical bone; genesis and microarchitectural features

The present paper presents a scanning electron microscope (SEM) analysis of the genesis and microarchitecture of experimentally induced cortical entry fractures in porcine scapulae impacted at velocities ranging from 54 to 897 m/s. SEM observation was conducted on polyurethane replicas cast from negative silicone moulds. Analysis of the sequence of fracture processes operative during projectile impact revealed the presence of ring cracks at the site of impact, confirming that penetration in sandwich bones is achieved by cone crack propagation. Despite impulsive loading, two forms of plastic deformation were identified in the cortical bone surrounding the entry fracture up to a maximum velocity of 871 m/s. Microscopic radial and concentric cracks were associated with projectile impact, and the role of pores and pits as stress concentrators was captured. Possible underlying mechanisms for the observed plastic deformation are described, and the diagnostic utility of SEM analysis is presented.

A Brief Review of Scanning Electron Microscopy With Energy-Dispersive X-ray Use in Forensic Medicine

Scanning electron microscopy with energy-dispersive x-ray (SEM/EDX) analysis is an investigation whose potential has become increasingly important in the field of forensic research and diagnosis. We present the procedure to perform a well-carried-out SEM/EDX analysis on corpses affected by different types of injuries, such as blunt force trauma, ligature strangulation, electrocution, sharp force trauma, gunshot wounds, and intoxication. After the areas of forensic interest have been macroscopically identified, the sampling can be performed in 2 different ways: apposition of the double-sided graphite tape on the damaged area or performing the excision of a biological sample. In both cases, a proper negative control sample is required. In all cases, SEM/EDX analysis can detect exogenous microtraces consistent with the types of injuries involved. In blunt force trauma, microparticles of different nature deriving from the contact of the blunt instrument with the victim may be observed; in sharp force trauma, metal microtraces (Fe, Cr, Al, Ti) can be identified. In ligature strangulation, exogenous microtraces may be found in the cutaneous furrow. In electrocution, it allows to identify the pathognomonic metal pattern (Cu, Zn, Fe) of the "electric mark." In gunshot wounds, the main applications regards the detection of metal particles (Pb, Ba, Sb) of gunshot residues. Finally, in the analysis of intoxicants, it may identify traces of toxic substances. Thus, the authors conclude that SEM/EDX analysis can provide essential information to assist in the medicolegal investigation of death.

Look before washing and cleaning: A caveat to pathologists and anthropologists

Partially or totally skeletonized bodies are undoubtedly the most challenging scenario to deal with for forensic pathologists and anthropologists. Indeed, in such cases, being able to figure out the cause and manner of death is often tricky. Human remains require to be washed and cleaned before a thorough assessment of any signs of trauma. However, bones and any fragment of more or less putrefied soft tissues may be home to crucial traces for investigative purposes. They are often located in the context of apparently meaningless dirt and, sometimes they are even invisible to the naked eye. Therefore, their careless cleaning inevitably leads to an unintentional loss of such traces with a negative impact on subsequent investigations. For these reasons before proceeding with cleaning, exhaustive examination and sampling must be carried out. In particular fragments of soft tissues, even if putrefied, are absolutely not to be considered as a hindrance for forensic purposes, since they could still provide valuable information after histological examination. Finally, forward-thinking professionals should think about the possible presence of exogenous micro-traces of forensic concern and collect specimens to be analyzed through in-depth analyses, such as Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry (SEM/EDX). The present series of cases demonstrates that crucial forensic information can be obtained through the analysis of apparently meaningless residues and even of micro-traces not visible to the naked eye and mixed with trivial dirt.

Is it possible to detect lead derived from gunshot residues on decalcified human bone by means of a histochemical staining with sodium rhodizonate?

In this study we have evaluated the detectability of lead deriving from Gunshot Residues (GSR) on human bone using colorimetric techniques as well as the possible interferences of decalcification on the stainability of these particles. 22 well preserved cadavers were divided into two groups: group A enlisted 11 victims deceased because of gunshot injuries (bones and soft tissues sampled in correspondence of the entry wound of the bullet)- and group B, comprehending 11 victims deceased for natural causes (specimens sampled from intact skin areas). All the samples, after decalcification processes for bone specimens with a 14 % HCl solution, underwent standard histological procedures and were stained with hematoxylin and eosin (H&E), sodium rhodizonate (Na-R) and acidified sodium rhodizonate (Na-R-HCl 5 %). Two additional slides of soft tissues for each group were pre-treated with HCl 14 % before being stained with likewise staining. In group A, 10 samples out of 11 resulted to be negative to Na-R and Na-R-HCl 5% techniques while all the corresponding soft tissues resulted to be positive for the same staining. Additional soft tissue slides processed with 14 % HCl solution were negative in 10 cases out of 11. No sample in group B showed positivity to the staining procedures neither with nor without pre-treatment with 14 % HCl. The search for GSR residues on human bone is therefore not executable with Na-R and Na-R-HCl 5 % techniques since the essential decalcifying procedure modifies the stainability of the residues therefore adulterating the results.

Application of scanning electron microscopy in the auxiliary diagnosis of death caused by potassium chloride intravenous injection: a case report

To determine the cause of death, in addition to routine autopsy, some assisted techniques are imperative to achieve a definite diagnosis. Herein, we report a case of 36-year-old man who was found dead in his apartment. Medical drug containers (potassium chloride, zolpidem, and propofol) and medical instruments (syringes and indwelling needles) were also found at the scene. An autopsy revealed large amounts of whitish foamy and brown liquid in the trachea and bronchi, and histopathological findings showed remarkable pulmonary congestion and edema. An injection mark with hemorrhage on the right wrist was found on external examination. Results of forensic pathology excluded the presence of mechanical injuries, mechanical asphyxia, embolism, and other fatal diseases. The data of toxicological analysis showed that concentrations of zolpidem and propofol in blood were appreciably higher than the therapeutic dose but they did not reach the absolute lethal dose. Moreover, the level of potassium in the blood and vitreous humor was higher than the expected concentration after death. A scanning electron microscope (SEM) combined with energy-dispersive X-ray microanalyzer (EDX) was subsequently applied to assess the skin samples collected from bilateral wrists. Ultrastructural observation discovered continuous visible interruption of the skin around the injection mark, and energy spectrum analysis revealed statistically significantly higher potassium content of the skin over the right wrist than the left wrist. Comprehensive analysis concluded that the deceased had died of potassium chloride intravenous injection under the zolpidem and propofol effects.

Forensic - Pathological SEM/EDX analysis in prosecution of medical malpractice

The retention of gauze within the mediastinum is considered an exceptional finding. We are presenting the case of a woman, affected by aorto-mitral valvulopathy, in whose mediastinum was found, during the autopsy, a gauzome without signs of active phlogosis, which had been "forgotten" in a previous surgery, acted 14 years before the death. A 39 y.o. woman had received surgical treatment of double aorto-mitral valve substitution and tricuspid plastic. At age 53, she successfully received surgery once again at a different hospital; she then started rehabilitation therapy, during which she deceased due to sudden hematemesis with infectious multi organ failure. During the autopsy, a 5 cm long surgical gauze was found in the mediastinum. A SEM/EDX (Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy) exam was ran on the foreign body and a sample of the same gauze used in the cardiac-surgical department of the hospital the victim had passed away in, to act a comparison between the two kinds of material. The exam showed a morphological difference between exogenous fibers incorporated within the gauzome and the control gauze. This case highlights the diagnostic and interpretative challenges in finding a foreign body within the mediastinum without signs of active phlogosis. SEM/EDX investigations executed on the gauzome and a "control gauze" allowed the attribution of malpractice to the first hospital the victim had been operated in 14 years before the exitus. The SEM/EDX exam confirms its importance in correctly identifying the case, which becomes an example for similar happenings.

The detection of gunshot residues in the nasal mucus of suspected shooters

The identification and quantification of metallic residues produced by gunshots, called gunshot residues (GSR), provide crucial elements in forensic investigations. The research has been largely focused on their collection onto the hands of suspected shooters, but the method is often burdened by risks of contamination. This research was focused on the possibility of sampling GSR trapped inside the nasal mucus of consenting shooters. Samples of the nasal mucus of "blank" control subjects and shooters were chemically analysed by Instrumental Neutron Activation Analysis (INAA), for residues of antimony (Sb) and barium (Ba), while lead (Pb) was excluded as ubiquitously environmental contaminant and due to high instrumental quantification limit (IQL) of INAA for this element. Shots were fired using two types of weapons (pistols and revolvers) and different firing sequences. The mucus was sampled at different times: immediately after the shots, after 30-60-120 and 180 min. Different amounts of Sb and Ba were detected between controls and shooters, witnessing the ability of the nasal mucus to retain GSR at concentrations significantly different even from the highest basal levels. Moreover, in order to simulate actual cases, nasal mucus from five groups of shooters was sampled after different shots with the same weapon and cartridges, immediately and after 1, 3, 12, and 24 h. The highest values were always found in the first 3 h from firing, for both weapons. Interestingly, for all the weapons, significant Sb and Ba concentrations were also found up to 12 h after firing, contrary to what occurs on hands, even though a progressive decrease was detected, with values below the detection threshold only after 24 h, thus demonstrating that GSR are persistent in nasal mucus. These first results proving that both Sb and Ba were qualitatively detectable in the nasal mucus of shooters indicate that the chemical analysis of the nasal mucus of suspected shooters may represent a promising tool in the forensic field since it is less burdened by problems related to sampling or contamination than the usual sampling on hand, providing that ammunitions employed contain Ba and Sb.