International Journal of Legal Medicine最新文献

Forensic microbiology allows identification by microbiome analysis when human DNA analysis is limited. However, microbiome-based approaches have not been widely used in forensic medicine. The spatial and temporal stability of microbial communities in response to environmental exposures represents a serious challenge. This study investigates the dynamics of skin and saliva microbial markers in response to environmental exposure to advance their forensic applicability. We selected 8 characteristic microorganisms (Finegoldia magna, Corynebacterium tuberculostearicum, Cutibacterium acnes for skin; Haemophilus parainfluenzae, Streptococcus oralis, Prevotella melaninogenica for saliva; Achromobacter, Pseudomonas as environmental markers) and developed two multiplex amplification systems for capillary electrophoresis detection. A longitudinal exposure model (0-120 days) under controlled indoor and dry environment was applied to 420 skin and saliva samples from 10 subjects. Saliva samples exhibited significant microbial community shifts between environments (R² = 0.4137). Dry environment preserved community structure better, evidenced by delayed inflection points in markers' proportions and stronger clustering in PCoA. Redundancy analysis correlated microbial markers with temperature and humidity, and this correlation varied. The microbial markers remained detectable after 120 days of environmental exposure and were able to provide information on community characteristics and deposition time. This study explored the effects of environment and time on microbial communities and the response patterns of microbial markers to temperature and humidity. It is expected to provide help for forensic microbial research related to environmental exposure.

Due to the complexity of the decomposition process and all the variables affecting it, there are many factors that have not been thoroughly examined. The impact of different soil types on decomposition of buried remains has received relatively little attention. This study sought to investigate the impact of three soil types on decomposition. Fourteen piglet carcasses were used to assess and compare the decomposition patterns and rates that take place in dolomite and quartzite (two soil types common in the city of Johannesburg, South Africa), as well as in tailings from gold mines (another common feature in southern Johannesburg). Each piglet was buried in a container filled with one of these soil types (four for Dolomite, five for quartzite and mine tailings) and was periodically partially exhumed to record Total Body Score progression as thermal energy (measured in Accumulated Degree Days) accumulated. Soil samples were also taken to record the soil's water content and pH level. The decomposition of the dolomite and mine tailing-interred piglets was found to differ significantly, with the latter progressing more rapidly. Dolomite was also consistently the soil type with the lowest water content and the least pH fluctuation, while quartzite had the highest water content and the most significant changes in pH over the course of the experiment. While this study has experimental limitations, it provides novel results that will help forensic practitioners understand subterranean decomposition in South Africa, and possibly other countries with similar climates and soil types.

Background and aim: Skeletal remains are sometimes discovered with the mandible missing from the skull due to external factors such as environmental conditions or scavenger activity. The absence of the mandible reduces the accuracy of forensic identification methods, including facial reconstruction. Although we previously established a two-dimensional method for estimating mandibular measurements (e.g., bicondylar breadth) commonly used in forensic practice, no method has yet been developed for estimating the entire three-dimensional mandibular shape. Therefore, the aim of this study was to establish a method for three-dimensional estimation of a missing mandible from the remaining cranium using an image analysis technique based on homologous modeling theory.

Materials and methods: Postmortem CT images of 200 Japanese subjects were used to create homologous models of the cranium (8,739 vertices) and mandible (4,255 vertices), ensuring that all samples contained the same number of vertices. Principal component regression analysis was then performed using the three-dimensional point cloud data obtained from each homologous model to construct a three-dimensional estimation model. Estimation accuracy was subsequently validated using separate samples.

Results: The mean error between all corresponding vertices of the estimated mandible and the actual mandible (ground truth) was 2.324 ± 0.659 mm. In addition, visualization analysis using multidimensional scaling confirmed that most of the estimated shapes were distributed close to the ground truth.

Conclusion: The estimation method developed in this study demonstrated a satisfactory degree of accuracy, suggesting its potential usefulness for three-dimensional estimation of missing mandibular morphology.

Postmortem interval (PMI) estimation is mandatory in any forensic investigation. Although it remains a very challenging task, particularly in skeletonized human remains. Luminol chemiluminescence has been explored as a tool for PMI estimation, however, its application requires further experimental validation to ensure accuracy and reproducibility. The present research aims to increase the objectivity of PMI estimation by quantifying the light emission from the luminol chemiluminescence reaction. For this purpose, a sample of clavicles collected from 24 adult individuals of both sexes, with known PMI ranging from 7 to approximately 500 years, was selected. After being reduced to powder, the samples were analyzed on a CCD camera with an image intensifier, and the reaction Ipeak was measured. The results obtained revealed a clear inverse relationship between PMI and Ipeak values. A segmented regression analysis identified a statistically supported threshold at approximately 30 years postmortem, distinguishing a variable early postmortem phase from a long-term phase characterized by consistently low and minimally variable chemiluminescence intensities. This pilot study supports the validity of quantifying the luminol chemiluminescence reaction as a feasible and informative presumptive screening tool for PMI estimation, with potential applicability in distinguishing remains of forensic interest from those of archaeological relevance.