Fragment analysis in forensic anthropology

The Future Is Now: Unraveling the Expanding Potential of Human (Necro)Microbiome in Forensic Investigations

The relevance of postmortem microbiological examinations has been controversial for decades, but the boom in advanced sequencing techniques over the last decade is increasingly demonstrating their usefulness, namely for the estimation of the postmortem interval. This comprehensive review aims to present the current knowledge about the human postmortem microbiome (the necrobiome), highlighting the main factors influencing this complex process and discussing the principal applications in the field of forensic sciences. Several limitations still hindering the implementation of forensic microbiology, such as small-scale studies, the lack of a universal/harmonized workflow for DNA extraction and sequencing technology, variability in the human microbiome, and limited access to human cadavers, are discussed. Future research in the field should focus on identifying stable biomarkers within the dominant Bacillota and Pseudomonadota phyla, which are prevalent during postmortem periods and for which standardization, method consolidation, and establishment of a forensic microbial bank are crucial for consistency and comparability. Given the complexity of identifying unique postmortem microbial signatures for robust databases, a promising future approach may involve deepening our understanding of specific bacterial species/strains that can serve as reliable postmortem interval indicators during the process of body decomposition. Microorganisms might have the potential to complement routine forensic tests in judicial processes, requiring robust investigations and machine-learning models to bridge knowledge gaps and adhere to Locard's principle of trace evidence.

Age estimation by evaluation of obliteration of the palatine sutures: a scoping review

The age estimation (AE) of human remains is a challenging task since it is dependent on the state in which these remains are found. Since the macroscopic evaluation of palatal sutures has been proposed as a method for AE, the aim of this study was to review the literature on this method, considering that the cases of edentulous elderly are among the greatest challenges in anthropological and forensic contexts. A scoping review was performed using a specific search strategy in PubMed, Web of Science, SciELO, LILACS, and Google Scholar. The search identified 13 articles, among which the USA yielded the most information with 3 articles. Only 1 study was identified in Latin America (Peru). There was great diversity regarding the origin of samples, and the studies were carried out on both historical and modern populations. Only 6 articles exceeded the average sample size (168.08) and 4 articles studied samples of fewer than 100 individuals. Although 6 different methods were identified, Mann et al.'s revised method was the most used. The selection of appropriate methods for AE depends on what skeletal elements are present and the general age of the specimens. Although evaluation of the obliteration of the palatal sutures has been found to be simple and promising for AE in individuals over 60 years of age, this method has been reported to have less precision than other more complex methods, which makes the use of a combination of methods necessary to increase the level of confidence and the percentage of success. Further research could resolve this weakness, and methodological refinement (perhaps the digitization and automation of processes, or the application of Bayesian methodology) could provide the necessary solidity to comply with international standards in the forensic scenario.

Two caseworks for one gene: successful species identification from compromised bone materials with the 12S rRNA

The availability of a reliable molecular assay in species recognition in forensic cases is of paramount importance when visual inspection or morphological methods are not exhaustive, especially from challenging samples. Here, two different caseworks involving bone samples founded during medico-legal outdoor investigations are presented. In order to exclude the human nature of the specimens and to determine the exact species they belong to, we proceeded with the molecular approach trying to generate sequences from the classical mtDNA markers cyt b and COI. However, they both gave critical results. For this reason, a short amplicon of ~ 150 bp of the 12S rRNA gene was used as an alternative.This short fragment was sufficient to identify the biological origin of the bone specimens with a high degree of certainty leading to the exclusion of their human nature. This work highlights the utility of the 12S rRNA and underlines the importance of deepen the choice of alternative shorter markers with respect to the classical ones, in order to achieve species identification even from challenging and degraded material in forensic criminal and wildlife caseworks.

Detection of bone particles in non-carbonate soils

A routine geologic test for the presence of carbonate minerals in soil is the application of dilute hydrochloric acid (HCl) and observation for an effervescent reaction. This study tests whether non-carbonate soils can exhibit effervescence in the presence of HCl if bone particles are present in the soil. Five bone fragments displaying various taphonomic alterations were ground and sieved to achieve uniform particle size fractions. A non-carbonate soil was mixed with each bone particle fraction, and 1 molar HCl solution was applied while observing the reaction using a stereo microscope. All tests resulted in the effervescence of bone particles, which could be easily located within the soil based on the presence of small bubbles surrounding the bone particle. These results show that a simple, quick, cost-effective test can be used to presumptively determine whether soil may contain bone particles, even if they are too small to be identified morphologically. Results also suggest that, since bone particles in soil can produce the same type of effervescence expected in carbonate soil, additional tests may be needed to determine the source of an effervescent reaction. These findings also highlight the insight that can be gained through interdisciplinary discussions and investigations.