International Journal of Legal Medicine最新文献

Massively parallel sequencing allows for integrated genotyping of different types of forensic markers, which reduces DNA consumption, simplifies experimental processes, and provides additional sequence-based genetic information. The STRseqTyper122 kit genotypes 63 autosomal STRs, 16 X-STRs, 42 Y-STRs, and the Amelogenin locus. Amplicon sizes of 117 loci were below 300 bp. In this study, MiSeq FGx sequencing metrics for STRseqTyper122 were presented. The genotyping accuracy of this kit was examined by comparing to certified genotypes of NIST standard reference materials and results from five capillary electrophoresis-based kits. The sensitivity of STRseqTyper122 reached 125 pg, and > 80% of the loci were correctly called with 62.5 pg and 31.25 pg input genomic DNA. Repeatability, species specificity, and tolerance for DNA degradation and PCR inhibitors of this kit were also evaluated. STRseqTyper122 demonstrated reliable performance with routine case-work samples and provided a powerful tool for forensic applications.

Brodifacoum exerts its antagonistic effect against the metabolism of vitamin K, an essential component in the synthesis of blood coagulation factors. This effect ultimately hinders the blood's capacity to clot effectively, rendering it a commonly employed rodenticide. Instances of lethal poisonings are exceedingly rare owing to expeditious medical intervention and treatment. Within this report, we present a case of brodifacoum-induced homicide, wherein the patient exhibited distinct clinical examinations and symptoms. Moreover, the patient's blood sample exhibited a noteworthy brodifacoum concentration of 0.681 µg/mL even after a period of 43 days following the incident of poisoning. Although an autopsy was not conducted due to religious restrictions, we endeavor to reasonably deduce the cause of death and furnish corroborative evidence for clinical diagnosis, treatment, and forensic examination in instances involving brodifacoum poisoning.

Introduction: Age Estimation has been considered as a human basic right, carried out through the use of tables for dental age assessment based on the chronology of tooth eruption. As such, the final aim of this investigation is to create tables with applicability to the Portuguese population, for the different scoring systems used and combined different statistical approaches.

Materials and methods: For this purpose, dental age assessment was achieved in all four third molars, using different scoring systems, in a total sample of 626 orthopantomograms (324 females, 302 males), aged between 12 and 25 years old, from the database population of Lisbon North University Hospital Center, approved by the Ethic Committee.

Results: The values of validation showed excellent results both on precision and on reproducibility. Mostly all methods showed statistically significant differences between the estimated age and the chronological age and, therefore, the presence of estimation errors. Kullman's and Mincer's methods are the ones with best applicability in the Portuguese population, in the lower third molars. The reliability measures (sensitivity, specificity and accuracy) values decrease as age increases.

Conclusion: A combination of the scoring systems as a protocol for dental age assessment in Portuguese nationality was established. Tables, for all the scoring systems used, were made with applicability in the Portuguese population.

Both hyper- and hypothermia are problematic in temperature based forensic time since death estimation. Hyperthermia may occur in infection, traumatic brain injury, and intoxication. Hypothermia is encountered predominantly in exposure. Sepsis may present itself clinically as hypothermic. Sepsis is not uncommon in the forensic setting and mostly occurs in the context of malpractice accusations. There is usually little overlap between sepsis and typical forensic time since death estimation scenarios of violent or otherwise suspicious deaths. In the presented case, hypothermia and time since death estimations did collide. An inmate was found dead in his jail cell. Wardens claimed they had visually approached him alive relatively shortly prior. Rectal temperature measurements, using two separate crime scene thermometers as well as temperature loggers, revealed low rectal temperature at relatively high ambient temperature. These findings suggested a much longer postmortem interval and consequently raised doubts about the stated timeline. The wardens' claims were however confirmed by camera recordings, which also allowed a reasonable estimate of the true time of death. The cause of death was confirmed as septic organ failure at autopsy, which explained low rectal temperature. The presence of WISCHNEWSKI-spots was noted. When the PRISM-method was applied to the temperature recordings, low rectal temperature at the time of death was detected successfully. However, adaptation of the underlying equation for lower "starting temperature" did not produce satisfactory results. It is concluded that even though hypothermia at the time of death may possibly be detected from temperature data, attempts at time since death estimation for cases of hypothermia by adaptation of the equation should be avoided.

Immunohistochemical analysis of platelet-derived growth factor receptor-α (PDGFR-α) was performed on human skin wounds obtained from forensic autopsy cases. Thirty human skin wounds were collected at different post-infliction intervals as follows: Group I, 4 h to 3 days (n = 16); Group II, 4 to 7 days (n = 7); Group III, 9 to 10 days (n = 3); and Group IV, 14 to 20 days (n = 4). Immunopositive reactions for PDGFR-α were not observed in the uninjured human skin specimens. In a semi-quantitative morphometrical analysis, the number of PDGFR-α-positive cells was observed increased in Group II, with the average number of PDGFR-α-positive cells being the highest in Group II. Additionally, in Group II, all specimens showed PDGFR-α-positive cells, with an average number of > 200 cells in five fields of view, suggesting a wound age of 4 to 7 days. Taken together, the immunohistochemical detection of PDGFR-α in human skin wounds can be a useful tool for wound age determination.

The use of genetic markers, specifically Short Tandem Repeats (STRs), has been a valuable tool for identifying persons of interest. However, the ability to analyze additional markers including Single Nucleotide Polymorphisms (SNPs) and Insertion/Deletion (INDELs) polymorphisms allows laboratories to explore other investigative leads. INDELs were chosen in this study because large panels can be differentiated by size, allowing them to be genotyped by capillary electrophoresis. Moreover, these markers do not produce stutter and are smaller in size than STRs, facilitating the recovery of genetic information from degraded samples. The INDEL Ancestry Informative Markers (AIMs) in this study were selected from the 1000 Genomes Project based on a fixation index (F_ST) greater than 0.50, high allele frequency divergence, and genetic distance. A total of 25 INDEL-AIMs were optimized and validated according to SWGDAM guidelines in a five-dye multiplex. To validate the panel, genotyping was performed on 155 unrelated individuals from four ancestral groups (Caucasian, African, Hispanic, and East Asian). Bayesian clustering and principal component analysis (PCA) were performed revealing clear separation among three groups, with some observed overlap within the Hispanic group. Additionally, the PCA results were compared against a training set of 793 samples from the 1000 Genomes Project, demonstrating consistent results. Validation studies showed the assay to be reproducible, tolerant to common inhibitors, robust with challenging casework type samples, and sensitive down to 125 pg. In conclusion, our results demonstrated the robustness and effectiveness of a 25 loci INDEL system for ancestry inference of four ancestries commonly found in the United States.

In sexual assault cases, it is crucial to discriminate between peripheral blood and menstrual blood to provide evidence for vaginal intercourse with traumatic injury. In this study, the menstrual blood mRNA markers progestagen-associated endometrial protein (PAEP), matrix metallopeptidase 7 (MMP7), and left-right determination factor 2 (LEFTY2) were evaluated by quantitative RT-PCR (RT-qPCR) for the discrimination of menstrual blood from peripheral blood and vaginal fluid. As a result, all markers with cutoff delta cycle quantification (ΔCq) values were specifically determined in menstrual blood among forensically relevant body fluids. Even though the changes in the expression levels of each marker differed during the menstrual cycle, all markers were determined to be positive in most of the randomly collected menstrual blood samples that were analyzed. Additionally, the markers with proposed cutoff ΔCq values could discriminate between menstrual blood and peripheral blood-mixed vaginal fluid samples. The determination of positive markers was less affected by storage temperature under dry conditions than under wet conditions, while PAEP was detectable in samples stored below room temperature under wet conditions. The detectability of PAEP was considered to be the result of its higher expression level compared with MMP7 and LEFTY2. In conclusion, menstrual blood markers for the RT-qPCR procedure evaluated in this study were highly specific for menstrual blood. The proposed procedure could be useful for discriminating between menstruation and traumatic bleeding in the female genital tract. In particular, PAEP is expected to be applicable to forensic casework samples because of its high specificity and robustness.

Interest in recovering DNA from the surface of ammunition evidence for genotyping has increased over the past few years. Numerous studies have examined a variety of methods to maximize DNA recovery from these types of challenging samples, but successful DNA profiling has been inconsistent. Low amounts of DNA and PCR inhibition due to metal ions have been suggested as the leading causes of poor results; however, no study quantitatively examined the presence of metal ions at various stages of the DNA analysis workflow from DNA collection through to amplification. In this study, the effectiveness of six different DNA collection and purification methods commonly used by forensic laboratories to process brass ammunition for DNA evidence was investigated. The amount of copper, zinc, and other metals co-recovered from fired and unfired brass casings during DNA collection (using numerous soaking, swabbing, and direct PCR protocols) was quantified via Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). This same panel of metals was subsequently quantified after DNA lysis and purification steps. Results demonstrated that low amounts of DNA, DNA damage, and degradation are more detrimental to STR typing results than PCR inhibition, as metal ions were successfully removed by all DNA purification methods tested. Furthermore, the use of metal ion chelators increased the amount of DNA recovered and number of reportable STR alleles. This research informs the forensic community on the most effective way to collect and process trace amounts of biological material from brass ammunition and similar evidence.

Medical imaging is a valuable source for facilitating empirical research and provides an accessible gateway for developing novel forensic anthropological methods for analysis including 3D modelling. This is especially critical for the United Kingdom (UK), where methods developed from modern UK populations do not currently exist. This study introduces a new approach to assist in human identification using 3D models of the paranasal sinuses. The models were produced from a database of 500 modern CT scans provided by University College London Hospital. Linear measurements and elliptic Fourier coefficients taken from 1500 three-dimensional models across six ethnic groups assessed by one-way ANOVA and discriminant function analysis showed a range of classification rates with certain rates reaching 75-85.7% (p < 0.05) in correctly classifying age and sex according to size and shape. The findings offer insights into the potential for employing paranasal sinuses as an attribute for establishing the identification of unknown human remains in future crime reconstructions.

The present study examines for the first time the emission patterns and olfactory signatures of 9 complete human corpses of different stages of decomposition. Air sampling was performed inside the body bags with solid sorbents and analysed by coupled gas chromatography-mass spectrometry after thermal desorption (TD-GC-MS). Furthermore, odour-related substances were detected by gas chromatography-olfactometry (GC-O). Sulfurous compounds (mainly dimethyl di- and trisulfide) were identified as most important to the odour perception. Around 350 individual organic substances were detected by TD-GC-MS, notably sulfurous and nitrogenous substances as well as branched alkanes, aldehydes, ketones, alcohols, carboxylic acids, carboxylic acid esters and ethers. A range of terpenes was detected for the first time in a characteristic emission pattern over all decomposition stages. Concentrations of the substances varied greatly, and no correlation between the emission patterns, the stage of decomposition and the cause of death could be found. While previous studies often analysed pig cadavers or only parts of human tissue, the present study shows the importance of analysing complete human corpses over a range of decomposition stages. Moreover, it is shown that using body bags as a kind of "emission test chamber" is a very promising approach, also because it is a realistic application considering the usual transport and store of a body before autopsy.