Journal of forensic sciences最新文献

This study evaluated the performance and limitations of the ForenSeq™ MainstAY chemistry on the MiSeq FGx® Sequencing System, which is approved for National DNA Index System (NDIS) use. This study included baseline performance, sensitivity and reproducibility studies, challenging casework samples, assessments of library plexities, comparisons with capillary electrophoresis (CE), standard versus enhanced PCR1 buffers, manual versus automated library preparation, and different flow cell types. To assess reproducibility across users, 33 samples were prepared by both an experienced and a novice user. Overall, the ForenSeq™ MainstAY Kit demonstrated high reliability with pristine samples and consistent performance across users, with minimal locus dropout until 62 pg. The kit outperformed CE for low-input and degraded samples, but limitations were observed at higher plexities. Increased sample numbers on a single flow cell disproportionately reduced read counts and locus recovery in degraded casework samples, while pristine samples were less affected. Strategic adjustments, such as batching degraded samples together or lowering plexity, may help mitigate these effects. Casework samples, including blood, touched items, bone, hair, and tissue, were tested with both standard and enhanced PCR1 buffers. In a 64-sample run (32 per buffer type), increased multiplexing reduced locus recovery in standard buffer samples, while the enhanced buffer improved recovery in 16 samples. Automated library preparation on the Opentrons OT-2 produced comparable or improved recovery relative to manual preparation, with no evidence of cross-contamination. These findings provide practical guidance for forensic laboratories adopting the MainstAY Kit, particularly in optimizing workflows for challenging samples and high-throughput sequencing environments.

Latent fingerprint research requires reproducible test materials that realistically mimic natural prints for the evaluation of development techniques. This study presents a novel artificial latent fingerprint solution that incorporates lipid components derived from the human body, simulating the composition of natural sweat and sebum, and combines them with traditional amino acid-based solutions. To improve solubility of non-polar lipid molecules, a 1:1 (v/v) mixture of n-hexane and isopropyl alcohol was used as the solvent, and the solution was loaded into printer cartridges to deposit standardized fingerprint-sized images on A4 paper, OHP film, and thermal paper. Development was carried out using established reagents, including ninhydrin, 1,2-indandione (1,2-IND), oil red O (ORO), and nile red (NR) for porous substrates; cyanoacrylate (CA) fuming with basic yellow 40 (BY 40), black, and fluorescent powders for nonporous substrates; and ThermaNin^®, 1,2-IND + polyvinylpyrrolidone (1,2-IND + PVP), ORO, and NR for thermal paper. The artificial prints showed broad compatibility across porous, nonporous, and thermal surfaces. Clear ridge detail and identifiable minutiae were consistently observed with most reagents, although NR exhibited limited fluorescence. All developed prints were identical, ensuring reproducibility for controlled testing. These findings demonstrate that the proposed solution provides a realistic and standardized tool for forensic validation of fingerprint development methods, including challenging substrates such as thermal paper.

This mixed-methods study investigates occupational burnout among forensic pathologists in Pakistan, incorporating a quantitative survey of 250 participants and qualitative interviews with 20 pathologists. This study investigated burnout using the Maslach burnout inventory (MBI) and qualitative interviews. As part of the quantitative analyses, independent-samples t-tests, ANOVAs, and MANOVA were conducted to examine the effects of gender, age, and professional experience on emotional exhaustion (EE), depersonalization (DP), personal accomplishment (PA), and total burnout. The interviews were thematically analyzed, providing context for the experiences being lived. The prevalence of burnout was average among most participants, with almost one-fifth of the respondents having high scores for EE and DP. Although the statistical tests did not indicate significant differences based on gender or age (ps > 0.05), professional experience was a significant predictor of PA, and more senior professionals reported higher resiliency and a reduced rate of burnout. These findings were replicated in the qualitative results, with heavy caseloads, poor institutional support, and trauma exposure being the main stressors. The main protective mechanisms are resilience, mentorship, faith, and family support. Burnout has adverse effects on forensic performance, which contributes to delays in reporting, mistakes, and threats to medicolegal reliability. Forensic pathology burnout is quantifiable and has specific outcomes. Caseload and institutional culture remained significant predictors, with resilience and mentorship serving as protective factors. To resolve burnout, the organization needs to change and implement relevant changes, redistribute the workloads, and acknowledge that mental health is a part of maintaining stable forensic practice.

When sexual assault evidence kits do not yield biological evidence demonstrating sexual contact, clothing such as undergarments is evaluated for the presence of semen. Menstrual underwear is a new type of undergarment and feminine product encountered as evidence in sexual assaults. They are composed of absorbent and leak-proof layers and can be washed and re-worn multiple times. The objective of this work was to determine a best practice for semen and DNA recovery from reusable menstrual underwear. Simulated postcoital samples were deposited on three different brands of menstrual underwear, and alternate light source evaluation failed for two of the three brands tested, though acid phosphatase testing was positive for all three brands tested. Testing of individual layers versus cuttings of a portion of the stain found that a full-depth cutting results in optimal biological sample recovery. Mock postcoital deposits were then washed once or twice and subjected to serological and DNA workflows, with varying results in acid phosphatase and P30 testing after washing once or twice between brands. However, sperm recovery was successful in all samples, and complete short tandem repeat (STR) profiles were obtained from both sperm and nonsperm fractions from all samples, regardless of washing status. With these findings, while sperm recovery has the highest likelihood of success with a full-thickness cutting, forensic scientists should be cautious in depending on ALS for stain location. Additionally, biological materials remain in these brands of menstrual underwear after washing, and therefore, biological material from previous sexual contact could remain and be detectable.

This paper documents efforts by members of the Crime Scene Investigation and Reconstruction (CSIR) subcommittee within the Organization of Scientific Area Committees (OSAC) for Forensic Science, in collaboration with researchers at the National Institute of Standards and Technology, to develop a documentary standard for performance assessment testing of terrestrial laser scanners (TLSs). Intended to be performed by forensic practitioners, this "Interim Performance Assessment" is specifically designed to be inexpensive, concise, and flexible, and is comprised of two parts that separately evaluate instrument accuracy and precision. This paper motivates and details the second of these test procedures, which uses a statistical methodology to assess whether an instrument's point coordinate precision has significantly changed over time. In this paper, the statistical details are reviewed, and the proposed test procedure is illustrated through two examples of longitudinal TLS data. The utility, scope, and limitations of the proposed test procedure are discussed in the context of instrument quality assurance.

Hair can trace drug use history, but prevailing extraction methods often struggle to fully extract analytes because of tight encapsulation by hair keratin. Since etomidate (ET) was controlled as a Category II psychotropic drug in China in 2023, developing an analytical method to accurately quantify ET and its metabolite etomidate acid (ETA) in hair is essential for establishing cutoff values in hair testing. This study compared extraction efficiencies of alkaline digestion and four solvent-assisted grinding methods (methanol, ammonium formate buffers, 10% formic acid) employing deuterated internal standards (ISs). The optimal method was validated by UPLC-MS/MS and applied to 53 authentic hair samples (11 also analyzed by alkaline digestion for relative extraction efficiency). The ammonium formate-formic acid buffer (pH 3.6) grinding method was proven to be optimal, providing high efficiency while preserving ET stability. It exhibited good linearity (r² >0.999) in a range of 0.005-5 ng/mg for ET and 0.002-10 ng/mg for ETA. Limits of detection (LOD) for ET and ETA were 0.001 ng/mg, with lower limits of quantification (LLOQ) being 0.005 and 0.002 ng/mg, respectively. All 53 samples had detectable ET (0.013-219.36 ng/mg), while ETA was quantifiable in only 32 samples (0.002-1.873 ng/mg), with ET/ETA ratios of 2.2-615.4. This study establishes a simple, reliable, and validated method for simultaneous quantification of ET and ETA in human hair, demonstrating high practicality for forensic and drug control applications.

This study investigated relationships between bullet mass, velocity, kinetic energy (KE), and fracture propagation in flat bones. Sixty full metal jacketed 9-mm bullets of different masses were fired at pig (Sus scrofa) scapulae. A chronograph measured bullet velocity prior to impact. Fracture characteristics were documented using standard terminology, counted, and measured at the entrance aspect, exit aspect, and overall per specimen. Few significant relationships between ballistic and fracture variables were found across the ranges tested, suggesting possible threshold effects. Bullet mass influenced velocity, suggesting that KE is the most practical variable for interpreting trauma in forensic contexts. Side-specific analyses showed entrance fracture length was primarily driven by long individual radial cracks, while exit fracture length reflected more cracks, more diverse crack types, and longer individual cracks. These findings provide a baseline for future research and underscore the utility of a standardized, quantitative, and surface-specific framework for documenting fracture characteristics.

This article presents a research-focused structured framework for validating empirical methods in digital and multimedia forensic science. Grounded in foundational principles from traditional forensic disciplines, the framework bridges methodological gaps by adapting validation strategies used in trace evidence, toxicology, and DNA analysis. It emphasizes reproducibility, legal defensibility, and operational applicability, integrating scientific guidance and recommendations from the National Academy of Sciences, the President's Council of Advisors on Science and Technology, and the National Institute of Standards and Technology, alongside the Federal Rule of Evidence 702 and the Daubert criteria. The framework comprises 10 iterative steps, including custom dataset control, pilot phase calibration, formalized error mapping, and embedded community review. It supports both full empirical validation and interim litigation-focused adaptation, enabling forensic practitioners to meet evidentiary standards without compromising scientific integrity. By elevating statistical planning, transparency, and reproducibility, the framework advances the credibility and courtroom readiness of digital and multimedia forensic methods.

Falling bullets, resulting from celebratory or random gunfire, represent a predictable yet often overlooked public safety problem. Unlike classical firearm injuries, they usually lack external findings typical of close or intermediate-range gunshot wounds, which complicates diagnosis, medico-legal evaluation, and judicial processes. Children and other vulnerable groups are disproportionately affected, leading to preventable mortality and significant medico-legal and social implications. We report the case of an 11-month-old infant who died after being struck by a falling bullet during a wedding celebration. The external examination revealed only a small entrance wound without soot deposition or tattooing. At autopsy, a depressed fracture of the right parietal bone was identified. The bullet penetrated through the parietal lobe and caused fatal damage at the level of the medulla oblongata. Falling bullets lose their initial velocity and rotational stability during ascent and descent, resulting in yaw and cavitation effects upon impact. Despite relatively low kinetic energy, these mechanisms can produce devastating intracranial injuries, particularly in children with thinner and more elastic skulls. Falling bullets are entirely preventable causes of death and injury. Effective legislation, strict enforcement, community-based awareness campaigns, and multidisciplinary collaboration are essential to reduce their occurrence. This case highlights the medico-legal importance of recognizing falling bullet injuries and underscores the urgent need for public health and legal measures to prevent such tragedies.

This study monitored the transfer of inorganic and organic gunshot residues (IGSR and OGSR) in cases where indirect exposure might be questioned, such as during arrests. Mock arrest scenarios (n = 180) were created to assess the effect of two variables on the secondary transfer. First, the level of contact between the detained and the officer (low, medium, and high) during the arrest protocols. Second, the activities preceding the arrest include situations where the officer or person of interest (POI) discharges a firearm or handles a gun without firing. Additionally, measures to mitigate the risk of GSR transfer from the arresting officer and surfaces were evaluated. This included variables like hand washing, wearing various types of gloves, and bagging the POI's hands during transport in a police vehicle (n = 70). All samples underwent screening (ECD and LIBS) and confirmatory analysis (SEM-EDS and LC-MS/MS). The results indicated that IGSR and OGSR behave differently, with their transfer and persistence varying according to the level of contact, activities, and exposure prior to arrest. Secondary transfer was observed in 69% of the experiments but was less likely to occur for OGSR than for IGSR. The OGSR was more prone to loss, as it was not detected in 93% of the medium- and high-contact scenarios. Preventive measures such as hand washing, wearing nitrile gloves, or bagging hands helped decrease the characteristic IGSR particle counts from 5-80 to none-11. These findings enhance the current knowledge of IGS/OGSR transfer and persistence while providing recommendations for arrest protocols and evidence collection.