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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., (© 2024. The Author(s).)

Microenvironments play a significant part in understanding the post-mortem interval in forensic taphonomy. Recently, the value of weathering factors in relation to obtaining a PMI has been investigated further. In this study, observations were made to calculate the length of time it takes for three different bone elements (femur, rib, and scapula) to bleach in a UK summer and winter. This research also investigated whether there were any physicochemical modifications to the bone caused by bleaching. Porcine femora, scapulae, and ribs were placed into open and shaded areas of an outdoor research facility located in Oxfordshire, UK, during summer (July-Sep) and winter months (Dec-Mar). The specimens were monitored at 3-week intervals using photography, and an observational scoring method was developed to quantify the extent of bleaching. As temperatures are typically much lower in the UK compared with warmer climates, a controlled indoor-simulated desert experiment was also undertaken to be used as a control. This allowed sun bleaching and changes to the bone chemistry to be monitored in a controlled, high-UV environment for comparison with the UK outdoor experiments. Fourier transform infrared spectroscopy (FTIR) was employed to analyze physicochemical modifications to both the mineral and organic components of the bone. The FTIR was used to calculate crystallinity index (CI), mineral to organic ratio, and the relative amount of carbonate concentrations. Weather data was collected and a positive correlation was found between both ultraviolet (UV) levels and accumulated degree days (ADD) when compared with observational bleaching scores. Bleaching (whitening) of the bone samples occurred in both seasons but at different rates, with the bleaching process occurring at a slower rate in winter. During summer, the initial bleaching process was evident at 6 weeks, and by 9 weeks, the bones were an off-white colour. During the winter period, whitening of the bone started at 9 weeks; however, only the scapula and rib samples displayed a similar off-white colour. This colouration was observed at 13 weeks rather than at 9 weeks. The desert simulation samples started bleaching in a similar pattern to the outdoor samples after 1 week but the bones did not fully bleach. The bone chemistry, based on physicochemical properties obtained from the FTIR, showed a significant statistical difference between the simulated desert and winter season when compared against a control sample. For the winter samples, the mineral to organic ratio was significantly higher than that in the control, suggesting a reduction in the proportion of organic. For the samples in the simulated desert environment, the crystallinity index was significantly higher than that in the control samples, suggesting an increase in crystallinity. The results of this experiment support the fact that it is possible to achieve bleaching in a UK environment and that the minimal time frame for this to occur differs in seasons.

The research and analysis of gunshot residues has a relevant role in the examination of gunshot wounds. Nevertheless, very little literature exists concerning gunshot wounds on charred material. In this study, 16 adult bovine ribs (eight still with soft tissues and eight totally skeletonized) underwent a shooting test with two types of projectiles (9 mm full metal-jacketed bullet and 9 mm unjacketed bullet). Each rib then underwent a charring process in an electric oven, reaching the stage of complete calcination at 800°C. The area of each entrance wound was analyzed before and after the carbonization process via a scanning electron microscope (SEM) equipped with an energy dispersive X-ray analyzer (EDX). In each sample, metallic residues composed of lead, barium, and antimony were found. These metallic residues were thus preserved also after exposure to the extremely high temperatures reached within the oven, especially with unjacketed bullets, although the particles seem to be more irregular in shape as a result of the heating process. In conclusion, this study proved that gunshot residues survive extremely high temperatures and can be detected via SEM/EDX even in cases of charred tissues.

In literature, many studies have been performed in order to investigate the presence of GSR ("gunshot residue") and metallic residues in general with radiological techniques on several types of material, but the survival of metallic residues on charred samples has never been systematically performed. In this study, 31 adult bovine ribs underwent a shooting test. Every rib was shot with a single bullet, at a near-contact shooting distance, using two kinds of projectile: 17 samples were shot with a full metal-jacketed bullet and the remaining 14 with an unjacketed bullet. After the shooting test, every rib underwent a "charring cycle" in an electric oven up to 800°C. Every sample underwent radiological investigation with conventional radiography, before and after the burning process, to evaluate any changes in number and distribution of metallic residues. Radiographs showed survival of radiopaque residues in every sample, even after the charring process, especially when the bullet used was of the unjacketed type.

Determinations of chronologic age are of great importance in forensic science. At present the aspartic acid racemization method on teeth provides one of the best means in adult individuals. However, if teeth are not available, some other stable tissue has to be used. In this study, the applicability of cartilage from the ribs has been tested. Specimens of rib cartilage were obtained at autopsy from 24 individuals aged 0.2-96 years. An acid-soluble peptide (SP) fraction and an insoluble collagen-rich (IC) fraction were prepared, and the ratio of D/L aspartic acid was determined using the HPLC technique. The correlation coefficient between the D/L ratio and age was r = 0.91 in SP and r = 0.97 in IC. It thus seems as if cartilage from non-weight-bearing areas may be a useful source of tissue for the estimation of chronologic age with the aspartic acid racemization method when teeth are not available.