Forensic Science, Medicine and Pathology最新文献

Saliva is a frequently encountered body fluid at crime scenes, however currently there are no definite means to rapidly identify a body fluid as being saliva. In this study, a novel detection method for saliva using a modified Loop-mediated Isothermal Amplification (LAMP) integrated with CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeat-CRISPR associated protein) and LFA (Lateral Flow Assay) was developed to detect the expression of a saliva-specific gene: follicular dendric cell secreted protein (FDCSP). To determine the specificity of the assay, RNA from saliva plus other commonly encountered body fluids was tested (peripheral blood, semen, vaginal fluid, and menstrual blood): positive results were only observed from RNA extracted from known saliva samples and RNA from all the other body fluids exhibited a negative result. To assess the reproducibility, triplicates were used from one saliva sample, and the assay was performed on three different days: positive results were observed from all triplicates. The limit of detection was 2^-6 (0.3906 ng RNA) or 2^-7 (0.1953 ng RNA). This preliminary study for the identification of saliva requires no complex equipment and is easy to perform, offering an alternative means for body fluid identification.

There are only few reports on the neuropathologic findings of fire victims. We investigated brain tissues of a 44-year-old and a 77-year-old man for neuropathologic examination with dehydration, embedding in celloidin, sectioning at 400 μm, and staining with gallocyanin. Microscopically, neurons were less well stained than those from an 87-year-old woman who died of cancer and whose brain had been fixed in formalin for three months. Glial cells were optimally stained. We observed local, laminar and disease-related qualitative and quantitative differences in the amygdaloid complex, temporal allo- and isocortex together with hyperchromatic staining of the medullary layer in the temporal lobe of both fire cases. The vasculature was well preserved and free of blood cells or clotted blood. The heat in fire deaths apparently acts as a kind of fixation, similar to the intention of formalin use, without the confounding effects of agonal and postmortem factors. Heat is most likely a major factor in microwave fixation. Thick gallocyanin-stained sections allow intuitive visual diagnosis of local and laminar neuronal degeneration or gliosis and have the potential to enhance and refine neuropathology-related diagnoses.

Purpose: Superfecundation, the fertilization of two oocytes by different spermatozoa within the same ovulatory cycle, can result in monopaternal or heteropaternal dizygotic twins. While monopaternal superfecundation is more common, heteropaternal superfecundation is rare and typically seen in disputed paternity cases. This study presents a case of heteropaternal superfecundation confirmed through forensic DNA analysis and reviews its occurrence in existing literature.

Methods: A forensic investigation was conducted in a court-ordered paternity case involving dizygotic twins, their mother, and an alleged father. Buccal swab samples were collected and analyzed using multiplex amplification of 19 STR markers and the amelogenin locus. A second DNA test confirmed the results. Additionally, a dataset of 2,679 paternity tests over 10 years was examined to estimate paternity exclusion rates in twin cases.

Results: Genetic analysis confirmed the alleged father's paternity of twin 1 but not twin 2, with 14 out of 19 STR loci showing absent alleles in twin 2. The 10-year dataset showed 553 paternity exclusions (20.64% of cases), with 31 involving twins, of which one case (3.23%) was identified as heteropaternal superfecundation. No significant difference was found between paternity exclusion rates in twin and non-twin cases.

Conclusions: This case underscores the value of forensic genetic testing in detecting heteropaternal superfecundation, a rare occurrence with legal and social implications. Advances in DNA analysis may lead to more frequent identification of such cases.

Forensic genetics faces significant challenges in the evolving landscape of DNA mixture analysis. This paper highlights the complexities associated with stochastic effects and artifacts in degraded or low-quantity samples and explores the primary objectives of DNA mixture analysis, namely deconvolution and weight of evidence quantification. The study examines the efficacy of the software tool EuroForMix (EFM) in interpreting complex mixtures. Genetic profiles from two forensic cases processed in 2022 by the Brazilian National Institute of Criminalistics' DNA Forensic Laboratory were reanalyzed using EFM v.3.4.0, focusing on deconvoluting DNA mixtures and quantifying the weight of evidence. Results were compared with previous analyses conducted using a laboratory-validated spreadsheet, LRmix Studio (for computing LR), and GeneMapperTM ID-X (for deconvoluting mixtures). EFM demonstrated high efficiency in both deconvolution and weight-of-evidence quantification, showing improved LR values for various profiles compared to previous analyses. In the reanalyzed cases, weight of evidence calculations using EFM produced values comparable to those obtained with the laboratory-validated spreadsheet and superior LR values compared to LRmix Studio. The comparison of deconvoluted profiles using EFM and GeneMapperTM ID-X revealed mostly consistent results for the major contributor genotype, with EFM yielding equal or better outcomes in most profiles. Thus, EFM shows potential as a tool for DNA mixture analysis, including both LR computation and deconvolution. Despite these encouraging results, it is recommended that each forensic laboratory develop DNA mixture interpretation protocols that consider internal validation.

Estimation of the postmortem interval (PMI) of found bones is an important and challenging part of forensic osteology assessments. This study examined human long bones that had been taken from cemeteries and hoarded by a "bone collector". Based on the police investigation and own investigation into the length of grave leases in the pertinent cemeteries, the narrowed down PMI for the bones was between 20 and 100 years. Our aim was to evaluate the suitability of the UV-fluorescence and luminol methods in determining the PMI of these bones and to assess the reliability of the results for forensic practice. Based on macroscopic criteria, 201 bones were classified into various PMI groups. Freshly sawn bone surfaces were then assessed with UV-fluorescence and luminol. The UV-fluorescence examination showed a weak to mediocre correlation between the intensity of UV-fluorescence and the PMI estimated by macroscopic criteria. Surprisingly, the luminol test did not reveal a negative correlation between the degree of chemiluminescence and macroscopically estimated PMI. Within a PMI span of up to 100 years, the extent of UV-fluorescence can serve only as a rough indicator of PMI. Alone, the method does not suffice to identify forensically relevant PMIs. Likewise, the luminol test does not reliably distinguish between bone finds with and without forensically relevant PMI. Nonetheless, the assumption that a negative luminol-test still speaks for a historical find appears to be justified, and, at least in combination with other tests, the luminol test can be used.

This study aimed to develop and validate two simplified, one-step extraction methods coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous segmental analysis of psychoactive substances, specifically doxylamine (DOX), haloperidol (HAL), citalopram (CTP), sildenafil (SDF), and common illicit drugs in hair samples. A secondary objective was to apply these methods to a real-life forensic case involving suspected prolonged drug-facilitated crime (DFC) with suspected non-consensual exposure with financial implications.Two analytical methods based on one-step extraction protocols coupled with LC-MS/MS were developed and validated according to ANSI/ASB 036 standards. One method was based on ultrasonic solvent extraction (USE), while the other relied on passive solvent incubation (PSI). Hair samples from two victims were collected and segmented to assess chronic drug exposure. Analytical performance was evaluated in terms of linearity, sensitivity, accuracy, precision, matrix effects, recovery, and dilution integrity.Both methods demonstrated high sensitivity (LODs as low as 0.27 pg/mg), accuracy (bias within ± 15%), and precision (RSD ≤ 18.3%). Segmental analysis of Victim A's hair revealed DOX and HAL concentrations consistent with chronic, non-consensual administration. HAL was also detected in Victim B's scalp and leg hair, while DOX was absent. The segmental distribution patterns supported the hypothesis of prolonged sedative non-consensual drug exposure.This study presented a rare case of drug-facilitated crime involving chronic administration of HAL and DOX within an alleged deception-based context. The validated LC-MS/MS methods proved to be robust, cost-effective, and suitable for routine forensic toxicology. Segmental hair analysis provided critical retrospective evidence, reinforcing its value in complex DFC investigations. The interpretation remained confined to analytical evidence, without inferring intent.