International Journal of Legal Medicine最新文献

Forensic taphonomy is the study of postmortem changes of human remains for the purpose of answering legal investigative questions. Many variables can affect the pattern and rate of decomposition of remains, posing challenges for taphonomic studies and estimation of the postmortem interval. Given the gap in knowledge regarding the suitability of using frozen remains to extrapolate conclusions to fresh material, investigating the effects of freeze-thaw cycles followed by burial on human remains is vital for forensic practice and taphonomic research. This study explored the impact of a freeze-thaw cycle and subsequent burial on human tissue decomposition under semi-controlled field conditions. Fresh and fresh-frozen-thawed hands were buried at the Amsterdam Research Initiative for Sub-surface Taphonomy and Anthropology for 31.7 to 340.4 accumulated degree days. Decomposition was assessed using fluorescence measurements targeting protein and fluorescent oxidation products, and broader excitation-emission matrix measurements in skin, adipose, and muscle tissue. Decomposition trends varied primarily by treatment group: fresh samples generally aligned with expectations that protein levels would decrease over time while fluorescent oxidation products increased, whereas fresh-frozen samples deviated significantly from these expectations. Significant differences were found between protein and fluorescent oxidation products levels of fresh and fresh-frozen tissue at corresponding time points, indicating this method's potential in determining sample state. However, fluorophore peak monitoring in excitation-emission matrices did not prove useful in establishing decomposition trends or potentially distinguishing between sample states. Despite limitations inherent to pilot and human taphonomy studies, this study clearly demonstrates that differences exist in the decomposition of fresh and fresh-frozen tissue, and that these trends vary slightly by tissue type. We therefore conclude that frozen material cannot be considered a proper substitute for fresh tissue regarding taphonomic processes, and the methods used in this study show promise in being used to differentiate between pre-decomposition treatments.

The aim of this study is to investigate the potential of radiomic features extracted from postmortem computed tomography (PMCT) scans of the lateral cerebral ventricles (LCVs) to provide information on the time since death, or postmortem interval (PMI), a critical aspect of forensic medicine. Periodic PMCT scans, referred to as "sequential scans", were obtained from twelve corpses with known times of death, ranging from 5.5 to 273 h postmortem. Radiomics features were then extracted from the LCVs, and a mixed-effect model, specifically designed for sequential data, was employed to assess the association between feature values and PMI. Four model variants were fitted to the data to identify the best functional form to explain the relationship between the variables. Significant associations were observed for features, the most significant being the median Hounsfield Units (HU) within the LCVs (p < 9.47 × 10⁻⁹), LCVs surface area (p < 4.69 × 10⁻⁶), L-major axis (p < 2.17 × 10⁻⁵), L-minor axis (p < 1.30 × 10⁻⁴), and HU entropy (p < 4.16 × 10⁻⁴). Our findings align with previous studies, supporting a logarithmic model for PMI-related changes in LCV volume and mean HU intensity value. This study highlights the potential of PMCT-based radiomics as source of complementary information that could be integrated into existing methods for PMI estimation. Our results support the application of a quantitative imaging approach in forensic investigations.

Determining the time since deposition (TsD) of body fluid stains can provide crucial criminal information to forensic researchers. Although there are studies on inferring residual time through DNA and RNA markers, this requires high sample quality, and microorganisms, as a new type of marker with individual and tissue identification capabilities, have the potential for body fluid recognition and TsD inference. Blood and semen are the most common types of bodily fluid stains at crime scenes, but research on the inference of the TsD of these two types of stains through microorganisms still needs to be explored. Thus, this study collected samples of body fluid stains exposed indoors for up to 56 days and selected several microorganisms that were both liquid specific and related to residual time inference in blood (Methylobacterium and Sphingomonas) and semen (Gardnerella) stains via 16 S rRNA high-throughput sequencing. Furthermore, the microorganisms' ability to infer TsD was verified using qPCR in validation group samples stored under the same conditions, and two multiple logistic regression models were constructed. The average absolute deviation of differences between the predicted and actual retention times of the three types of body fluids in the test set using two estimation methods was 2.15 and 2.06 days, respectively. In conclusion, this study has discovered four novel microorganisms related to the retention time of blood and semen and has preliminarily constructed the TsD prediction models, providing a new direction for future forensic research on the inference of TsD in blood and semen stains.

Traumatic Brain Injury (TBI) represents one of the leading causes of disability and death globally, with a significant impact on public health. We present 12 cases (age 5-80 years old) of death due to TBI with different post-traumatic interval (PTI). The expression of S-100B and RIPK-1 in pericontusional zones of TBI were studied in forensic cases to understand the vitality and timing of injuries. The anti-RIPK-1 antibodies mainly stained the cytoplasm of the nerve cells. In 3 cases (48 to 56 years old with no other comorbidities; PTI: 2 days to 4 days) antibodies positive for RIPK-1 were found. In 5 cases (48 to 71 years old; PTI: 2 days to 12 days) astrocyte, oligodendrocyte and neurons positive for anti-S-100B were found. In 3 of these 5 cases both antibodies tested were positive. In 7 cases (5-80 years old; one with history of drug abuse, other with no comorbidities, PTI 0 h; ) the glial cells were swollen and the submeningeal glial limitans became immunopositive for S100B. Stain accumulations were also observed adjacent to the walls of cerebral vessels, sometimes within the intravascular compartment. The results of the study show that in subjects who suffered a TBI, the expression of RIPK-1 and S-100B at the level of neurons in the pericontusional area was significantly increased compared to the control group. Neurons were not stained for RIPK-1 in cases of sudden cardiac deaths and sudden deaths due to TBI but observed neurons became immunopositive for RIPK-1 some days after TBI. S100-immunopositive neurons were not seen in immediate deaths but were found in cases with survival up to 12 days. Results regarding S100B are in line with existing knowledge. The study of necroptosis with anti-RIPK-1 antibodies could be useful in understanding the extent of secondary injuries and survival time in forensic contexts. However, this is a pilot study and should be extended to a larger number of cases to achieve more reliable results.

Determining the time since deposition (TsD) and sex of saliva stains is crucial for revealing the time of the crime's occurrence and clarifying the nature of the crime. This process not only shortens the time required to solve the case but also helps narrow down the scope of investigation, thereby enhancing the efficiency of case resolution. Currently, the forensic study of the microbial composition in long-term saliva stains remains a relatively underexplored field. The purpose of this study was to explore the succession pattern of long-placed human saliva stains microbial communities and identify relevant microbial markers for estimating TsD and identifying the sex of the donor, in order to be an effective alternative tool for solving practical forensic cases. Therefore, in this study, saliva stains exposed to indoor environmental conditions for up to 140 days were collected and 16S rRNA full-length sequencing was performed using single-molecule real-time sequencing technology based on the PacBio sequencing platform. The study reveals that after 140 days of placement, the relative abundance of Firmicutes significantly decreased (p = 0.00304). At the genus level, the relative abundances of Streptococcus (p = 0.0008), Rothia (p = 0.0448), Gemella (p = 0.016), and Veillonella (p = 0.0208) also significantly decreased. Additionally, significant differences were found in the microbial communities between saliva stains from males and females (p = 0.00013). Then, we constructed a TsD estimating model for microbial community markers based on random forest, and the results showed that the mean absolute error was 9.59 days, and the accuracy of sex classification model based on stepwise logistic regression model and 4 bacterial markers was 84.21%. This indicates that saliva stains that have been in place for a long time still retain significant forensic value, and microbial markers can be used to determine the time since deposition (TsD) of dried saliva stains as well as to identify the sex of the donor.

DNA identification of human skeletal remains play a valuable role in the forensic field, especially in missing persons and mass disasters investigation. Hard tissues, such as bones and teeth, represent a very common kind of samples analyzed in forensic laboratories because often they are the only biological materials remaining. However, the major limitation in using these compact samples rely on time consuming and labor-intensive treatment of grinding them into powder before proceeding with the conventional DNA purification and extraction step. In this context, a novel DNA extraction assay, called the TBone Ex kit (DNA Chip Research Inc.), was developed to digests bone chips without powdering "as reported by Kitayama (JAMA 12:84-89, 2010)." Here, we simultaneously analyzed bone and tooth samples obtained by our police laboratory that belonged to 15 different forensic cases from Sardinia (Italy). The total of 27 samples were recovered from different scenarios and were exposed to extreme environmental factors, including sunlight, seawater, soil, fauna, vegetation and high temperature and humidity. The TBone Ex kit was used prior to the EZ2 DNA extraction kit on the EZ2 Connect Fx instrument (Qiagen), and high quality autosomal and Y-chromosome STRs profiles were obtained for the 80% of the cases, in a relatively short time frame. This study provides additional support for the use of the TBone Ex kit for digesting bone fragments/whole teeth as an effective alternative to pulverization protocols. We empirically demonstrated the effectiveness of the kit in processing multiple bone samples simultaneously, largely simplifying the DNA extraction procedure, and the good yield of recovered DNA for downstream genetic typing in highly compromised forensic real specimens. In conclusion, the results of this study appear useful for forensic laboratories, to which the various actors of the criminal justice system - such as potential jury members, judges, defense attorneys and prosecutors - require immediate feedback.

Background: Sexual violence (SV) while travelling internationally is underreported and pre-travel advice is often focussed on broader tourist safety concerns. International travellers who experience sexual violence face particular challenges. The aim of this paper was to analyse the attendances of people who disclosed having been subjected to SV during international travel to the Sexual Assault Treatment Unit (SATU) network in the Republic of Ireland.

Methods: Analysis of all people who attended the national SATU network who disclosed an incident of SV experienced during international travel, and comparison of these cases with domestic case attendances.

Results: During the 7-year period studied, there were 6,447 attendances to the national SATU network, with 443 incidents reported as occurring outside Ireland; in 66 separate countries. The mean age of international attendees was 26.61 years, with females representing 90.3% of cases. Where an incident occurred internationally, the patient was less likely to disclose drug ingestion in the 24 h preceding the incident (p < 0.001) and significantly less likely to be assaulted in the assailant's home (p = 0.009) when compared with domestic cases. Those who were assaulted internationally were significantly more likely to be assaulted by a stranger or recent acquaintance, i.e. ( p < 0.001).They were also more likely be assaulted in a location recorded as 'other indoors' (e.g. hotel, hostel etc) (p < 0.001). There was no significant difference in alcohol consumption (p = 0.115) or frequency of assaults occurring outdoors (p = 0.155).

Conclusion: Our study has shown that 7% of attendances to the SATU network followed incidents of SV that occurred during international travel. The majority of these incidents were disclosed as being perpetrated by a stranger or recent acquaintance, in an indoor setting with over half having occurred in Europe. Individuals who experience SV while travelling abroad should be encouraged to seek immediate medical attention and appropriate follow-up care upon returning home.

Postmortem interval (PMI) estimation, a parameter critical for solving criminal cases, remains a challenge. It has been suggested that elasticity of decomposing tissue may show a relationship to PMI. We measured elasticity of excised porcine skin at regular intervals for 17 days using a novel ultrasound device. Kruskal-Wallis test followed by Dunn's pair-wise comparison test was performed on the elastic modulus values from each time-point. We found statistically significant differences (p < 0.0001) between the elastic modulus values. Pair-wise comparison showed that tissue measured with a PMI of 1-4, 6-9, 10-14, and 16-17 days can be distinguished from each other based on elastic modulus values. An overall trend of increasing elastic modulus values with time was also observed. Histology and H&E staining of skin samples at PMI of 1, 5, 8, and 12 days showed increasingly prominent fibre bundles which may explain the observed trend. The results of our study suggest that estimation of PMI using an ultrasound device is promising and should be explored further.

In forensic practice, identifying the species of unknown bodily fluid stains can provide assistance in the qualitative analysis and investigation of cases, and vaginal fluid stains, as one of the common bodily fluid stains, are most commonly seen at the scene of sexual assault. At present, the commonly used vaginal peptidase or microscopic detection methods currently have drawbacks such as high false negative rates, poor sensitivity, and high requirements for sample integrity and background color. However, in forensic investigations, the test materials have specificity and scarcity, making it difficult to ensure their quantity and quality. Thus, in order to achieve rapid and sensitive detection of vaginal fluid stains, in this study, we combined nested PCR and isothermal amplification technology to construct a rapid detection system for suspicious vaginal fluid stains using lateral flow dipstick. This system achieves detection by detecting the specific marker microbial community Lactobacillus crispatus in vaginal fluid, and has a high sensitivity and accuracy, which can achieve detection at template quantities as low as 2.31 copies. More importantly, the system can achieve detection at a constant temperature of 37 °C without the need for complex instruments. It can provide rapid and sensitive identification results, providing assistance for subsequent forensic material extraction and individual identification.

Disaster victim identification and criminal investigations have intensified the demand of complex kinship testing. Compared to close relatives, distant relatives share fewer identical-by-descent genetic segments; therefore, more genetic markers are required to improve the system effectiveness. Driven by the progress of next-generation sequencing, several commercial or in-house panels, including a large number of genetic markers, have been developed and applied in forensic caseworks. However, few efficient panels are available for first cousins (FC) kinship testing. Here, we adopted the MGIEasy Pa-SNPs genotyping kit, a two-step multiplex PCR strategy to detect 2,009 SNPs, and evaluated their system effectiveness in complex kinship analysis. Samples from 10,000 pairs of relatives and unrelated individuals were simulated to evaluate the system power. Simultaneously, real samples were used to further confirm this, including 72 pairs of full siblings (FS), 52 pairs of uncle/aunt/-niece/nephew (UN), 92 pairs of FC, 79 pairs of first cousin once removed (1C1R), and 780 pairs of unrelated individuals. The results showed that this kit was sufficiently powerful in FS, UN, and FC versus unrelated kinship testing and could also discriminate part of 1C1R relatives against unrelated individuals. This method was also powerful in the kinship determination of FS versus UN, FS versus FC, FS versus 1C1R, and UN versus 1C1R kinship testing but had limited power to determine UN versus FC and FC versus 1C1R relationships. This study provides an effective strategy and guidance for complex kinship analysis in forensic practice.