Forensic Sciences Research最新文献

Currently, forensic death investigations in the Western Cape, South Africa do not account for vertebrate scavenging activity; however, previous research in the city of Cape Town has shown a significant impact on the rate of decomposition due to scavenging by the local Cape grey mongoose (Galerella pulverulenta). This pilot study aimed to develop a framework to more robustly quantifiably describe and analyse the scavenging behaviour of this species on a single clothed 60 kg porcine carcass in a forensically significant location in Cape Town (i.e., a region of the city with a proportionately large forensic case load). Feeding behaviours are the focus of this framework and analysis, but non-feeding behaviours in the immediate vicinity of the carcass are also distinguished and described. Additionally, it was assessed whether all behaviours varied in their frequency of occurrence as decomposition progressed. More than 40 h of mongoose interaction with the carcass were recorded using motion-activated infrared-capable wildlife trail camera videography. The highest frequencies of scavenging activity were observed in the abdominal and the eye socket regions of the carcass. Abdominal feeding largely involved soft tissue modification, whereas more intensive activity in the eye socket suggested a higher likelihood of hard tissue scavenger artefacts being found there. A Kruskal-Wallis test confirmed that some feeding behaviours occur more frequently during specific decomposition stages. For example, scratching is common during the earlier stages of decomposition, ostensibly to create an opening in the flesh. Twisting whilst biting was only observed in latter stages of decomposition, likely due to the increased toughness of the soft tissue as it desiccated. This pilot research offers detailed insight into scavenger behaviours previously unreported in the forensic taphonomic literature, and proposes a provisional method of quantifiable analyses of scavenger behaviours that extends what has previously been published in the forensic taphonomic literature. Local validation of the observations is planned, and international replication of the research for diverse scavenger guilds is encouraged.

Key points: Novel framework for detailed quantitative analysis of vertebrate scavenger behavior using the Cape grey mongoose as a model.First systematic study of scavenger behaviour in South Africa and likely Africa-wide.Cape grey mongoose preying on blow fly larvae, emphasizing the necessity of videographic documentation.

DNA transfer, whether intentional or not, is becoming an important part of forensic evidence gathering and analysis. This study seeks to determine the impact of liquid antibacterial soap and hand sanitizer use on the DNA present in the palms of hands that may potentially reduce direct transfer. Twelve volunteers were enrolled and typed. Afterwards, each palm was swabbed without considering previous activities to collect background DNA profiles. Subsequently, each subject washed his/her hands for 30 s with antibacterial soap first, and after with sanitizing gel and then air-dried them; after drying, each palm was immediately swabbed for DNA typing. The results of this study demonstrated that the possibility of recovering a complete profile from a hand swab is strictly related to previous activity: considering the results of the samples taken before handwashing, there is the possibility of having a median recovery of 80.01%, while it is very low (median recovery was 3.43%) after hand washing with antibacterial soap followed by alcohol-based hand sanitizer. Analyzing the results after handwashing, we were unable to detect any drop-in alleles. Moreover, we determined that in 11/12 samples, less than nine alleles were detected: considering that the kit used for the profiling could analyze 23 short tandem repeats (STRs), it is possible to conclude that we obtained inconclusive profiles. Based on the findings of the present study, it is more difficult to obtain a perpetrator's profile if he/she used liquid antibacterial soap and hand sanitizer immediately before the criminal action.

This study evaluates mathematical tools (principal component analysis, dynamic time warping, and the Kolmogorov-Smirnov hypothesis test) to analyse global and local data from dynamic signatures to reduce subjectivity and increase the reproducibility of handwriting examination using a two-step approach. A dataset composed of 1 800 genuine signature samples, 870 simulated signatures, and 60 disguises (30 formally similar or "autosimulated" and 30 random but different from usual) provided by 30 volunteers was collected. The first step involved global data analysis using principal component analysis and a hypothesis test performed for 62 global characteristics, and associations of these characteristics were analysed through calculations of multivariate distance followed by a hypothesis test. The second step involved the analysis of local characteristics including vertical and horizontal positions, speed, pressure gradient, acceleration, and jerk point-to-point, by using dynamic time warping followed by a hypothesis test. Optimization of sensitivity and specificity metrics of the hypothesis test was explored by varying its stringency and observing accuracy rates for the simulated and genuine groups. A P-value threshold of 1 × 10^-10 was found to be optimal, making the test more restrictive and yielding accuracy rates of 96.7% for genuine global data and 88.9% for simulated data. The same cut-off value for local characteristics provided an average accuracy rate of 95.4% for genuine samples and 94.7% for simulated samples, demonstrating high accuracy for both simulated and genuine samples. However, the method did not offer reasonable accuracy rates for disguises, consistent with observations in traditional handwriting examination. Our approach provided satisfactory results for forensic examination use. The visualization of graphs and signatures and analysis of all identifying elements of handwriting by the examining expert are still essential. In future studies, we plan to perform blind tests to validate our approach and propose a rigorous methodology.

In the realm of document examination, the identification of suspicious alterations to handwritten documents is an important factor in case characterization. Investigating the differences in gel pen ink compositions has significant implications. In this study, we used desorption electrospray ionization mass spectrometry (DESI-MS) to analyze the ink compositions of gel pens. The methodology involved the following steps. (i) Sample selection: a total of 227 gel pens available in the market were procured for the study. (ii) Pre-experimental parameter exploration: preliminary experiments were performed to optimize the experimental parameters. (iii) Analytical technique: DESI-MS was used to collect compositional data from the gel pen ink samples, without requiring pre-treatment of the samples. (iv) Data analysis: the obtained data were analyzed using the Davies-Bouldin index, Calinski-Harabasz index, and K-means algorithm for ink sample classification. The experimental findings indicated that DESI-MS is a viable method for examining the ink compositions of gel pens. Notably, the testing process is minimally destructive and does not necessitate pre-treatment of the samples. Furthermore, variations in the ink compositions were observed among different models of gel pens within the same brand, and the extent of the variation in the composition varied across brands. Additionally, there were instances in which the ink compositions of different brands of gel pens exhibited similarities.

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[This corrects the article DOI: 10.1093/fsr/owad058.].

[This corrects the article DOI: 10.1093/fsr/owad052.].

[This corrects the article DOI: 10.1093/fsr/owad046.].

[This corrects the article DOI: 10.1093/fsr/owae004.].