查看更多>>摘要：Abstract Survivability, the ability of a skeletal element to withstand taphonomic processes, is often equated to recoverability, the probability that an element will be recovered in a forensic context, and further misused to infer the likelihood that a forensic anthropologist will recover a particular element at a scene. Consequently, researchers have utilized notions of survivability to infer that a skeletal element may be recovered when justifying the necessity of various research endeavors. This is problematic because the factors impacting survivability are not always applicable in a forensic context; the ability of a bone to survive taphonomic processes may not align with the likelihood of recovery. Empirical recovery rates are presented from two distinct contexts, with data derived from the Forensic Anthropology Data Bank based on cases performed by the late J. Lawrence Angel (1914–1986) and cases done by the University of Tennessee Knoxville (UTK). Recovery rates may be influenced by factors beyond survivability, though we do not investigate the many considerations that might explain recovery rate variation between datasets. Rather, these data exemplify the conceptual differences between notions of survivability and rates of recovery in actual casework scenarios. Thus, it is proposed that researchers consider documented rates of recovery when providing rationale for forensic anthropology research endeavors, in addition to citing a rationale that is based on inferences of survivability. This ensures that the theoretical framework of future forensic anthropology research stems, primarily, from the premise of practical application.
Heidi G. SutherlandLarisa M. HauptKirsty M. WrightLyn R. Griffiths...
10页
查看更多>>摘要：Abstract Sanger sequencing of the mitochondrial DNA (mtDNA) control region was previously the only method available for forensic casework involving degraded samples from skeletal remains. The introduction of Next Generation Sequencing (NGS) has transformed genetic data generation and human identification using mtDNA. Whole mitochondrial genome (mtGenome) analysis is now being introduced into forensic laboratories around the world to analyze historical remains. Research into large pedigrees using the mtGenome is critical to evaluate currently available interpretation guidelines for mtDNA analysis, which were developed for comparisons using the control region. This study included mtGenomes from 225 individuals from the last four generations of the Norfolk Island (NI) genetic isolate pedigree consisting of 49 distinct maternal lineages. The data from these individuals were arranged into 2339 maternally related pairs separated by up to 18 meioses. Our results show that 97.3% of maternally related pairs were concordant at all nucleotide positions, resulting in the correct interpretation of “Cannot Exclude”; 2.7% of pairs produced an “Inconclusive” result, and there were no instances of false exclusion. While these results indicate that existing guidelines are suitable for multigenerational whole mtGenome analysis, we recommend caution be taken when classifying heteroplasmic changes as differences for human identification. Our data showed the classification of heteroplasmic changes as differences increases the prevalence of inconclusive identification by 6%, with false exclusions observed in 0.34% of pairs examined. Further studies of multigenerational pedigrees, however, are needed to validate mtGenome interpretation guidelines for historical case work to more fully utilize emerging advancements.
Colin I. ElliottTheresa E. StotesburyAaron B. A. Shafer
10页
查看更多>>摘要：Abstract The physicochemical changes occurring in biomolecules in degrading bloodstains can be used to approximate the time since deposition (TSD) of bloodstains. This would provide forensic scientists with critical information regarding the timeline of the events involving bloodshed. Our study aims to quantify the timewise degradation trends and temperature dependence found in total RNA from bloodstains without the use of amplification, expanding the scope of the RNA TSD research which has traditionally targeted mRNA and miRNA. Bovine blood with ACD‐A anticoagulant was deposited and stored in plastic microcentrifuge tubes at 21 or 4°C and tested over different timepoints spanning 1 week. Total RNA was extracted from each sample and analyzed using automated high sensitivity gel electrophoresis. Nine RNA metrics were visually assessed and quantified using linear and mixed models. The RNA Integrity Number equivalent (RINe) and DV200 were not influenced by the addition of anticoagulant and demonstrated strong negative trends over time. The RINe model fit was high (R2?=?0.60), and while including the biological replicate as a random effect increased the fit for all RNA metrics, no significant differences were found between biological replicates stored at the same temperature for the RINe and DV200. This suggests that these standardized metrics can be directly compared between scenarios and individuals, with DV200 having an inflection point at approximately 28?h. This study provides a novel approach for blood TSD research, revealing metrics that are not affected by inter‐individual variation, and improving our understanding of the rapid RNA degradation occurring in bloodstains.
Orianna ThomasAmanda BelunisRachel AlibozekEllen M. Hondrogiannis...
15页
查看更多>>摘要：Abstract Dokha is a tobacco product commonly used in Middle Eastern and Northern African regions. It is available in three blends purportedly corresponding to the degree of “buzz” experienced by the user. The “buzz” has been linked in part to nicotine levels, which are higher than those found in cigarettes and is believed to be the reason dokha is abused as a “legal high.” There have been reports of seizure activity from dokha users, and elevated concentrations of toxic metals have been measured in dokha tobacco. The purpose of this work was to determine whether we could use dokha's elemental content, measured by inductively coupled plasma–mass spectrometry, to link dokha back to its brand. This could aid investigators in identifying brands and/or distribution routes in the case of adverse effects resulting from dokha use. We measured the concentrations of Mg, K, Mn, Ni, Cu, Rb, Sr, and Ba in Medwakh, Nirvana, Scorpion, Enjoy, Kingdom, and Iconic dokha brands. Analysis of variance revealed statistical differences in concentrations of elements among groups. Discriminant function analysis (using leave‐one‐out classification) was 58.3% successful at differentiating brands. Enjoy dokha was the most, and Kingdom dokha the least, correctly classified among groups. Attempts to further link dokha blends back to light, medium, and heavy blends were less successful. These results indicate potential for using elemental content to discriminate among dokha brands. Our data may also help to understand the degree of additional processing and/or adulteration of dokha products available to users in the United States.
查看更多>>摘要：Abstract Footwear comparison is used to link between a suspect's shoe and a shoeprint found at a crime scene. Forensic examiners compare the two items, and the conclusion reached is based on class characteristics and randomly acquired characteristics (RACs), such as scratches or holes. An important question concerns the distribution of the location of RACs on shoe soles, which can serve as a benchmark for comparison. This study examines the probability of observing RACs in different areas of a shoe sole using a database of approximately 13,000 RACs observed on 386 outsoles. The analysis is somewhat complicated as the shoes are differentiated by shape and contact surface, and the RACs' locations are subject to measurement errors. A method that takes into account these challenges is presented. All impressions are normalized to a standardized axis to allow for inter‐comparison of RACs on outsoles of different sizes and contact areas, and RACs are localized to one of 14 subareas of the shoe sole. Expected frequencies in each region are assumed to be Poisson distributed with rate parameters that depend on the subarea and the contact surface. Three different estimation approaches are studied: a naive crude approach, a shoe‐specific random effects model, and an estimate that is based on conditional maximum likelihood. It is shown that the rate is not uniform across the shoe sole and that RACs are approximately twice as likely to appear at certain locations, corresponding to the foot's morphology. The results can guide investigators in determining a shoeprint's evidential value.
查看更多>>摘要：Abstract The highest levels of source association in forensic footwear comparison rely on the agreement between randomly acquired characteristics (RACs) identified on questioned and exemplar test impressions. These features are presumed to be randomly acquired and independent. However, independent acquisition does not necessarily mean these features will be uniformly distributed across an outsole. The aim of this research was to determine if the distribution of RACs in a research dataset could be described by an inhomogeneous Poisson point process based on tread contact and wear. To achieve this goal, RAC spatial frequency from an empirical dataset of shoes was compared against simulated and modeled data assuming a Poisson point process. Deviations in count between the empirical and simulated/modeled predictions were examined using a Poisson rate test and Moran's I. Results indicate that RAC frequency over 67%–79% of an outsole can be reasonably well explained as a Poisson point process or by a Poisson generalized linear regression model (non‐spatial GLM) with tread contact as a predictor. Moreover, if the predictor is extended to include both tread contact and wear, RAC counts over 84% of the spatial locations on an outsole are well‐explained (although autocorrelation persists). Overall, results indicate that RACs are not uniformly distributed in this dataset, most likely because the factors that dictate RAC development (friction, gait, etc.) are not uniformly distributed. Although this observation in no way negates the use of RACs in forming source associations, the value of a correspondence can differ depending on its spatial location.
查看更多>>摘要：Abstract Automotive glasses are important forensic evidence often recovered from crime scenes. Black ceramic prints on automotive glasses contains various elements in high concentrations. A portable X‐ray fluorescence spectrometer (pXRF) allows an instant and nondestructive analysis of various elements. In this study, the Bruker Tracer 5?g was used as the pXRF equipment. The NIST SRM612 glass standard was used to determine the limit of detection (LODs) of a pXRF and its optimal conditions. The acceleration voltages of 15, 30, and 50?kV were appropriate for measuring Si Kα (1.740?keV)–Ni Kα (7.473?keV), Cu Kα (8.042?keV)–Pb Lα (10.552?keV), and after Bi Kα (10.839?keV), respectively. The pXRF was used to compare 37 black ceramic prints on automotive glasses from the known source. The samples were divided into two groups: the Pb type and the Bi type. The samples were compared in pairs. The most appropriate and effective indicators for discriminating between the Pb and Bi type of black ceramic prints on automotive glasses were Zr Kα/Pb Lα and Cu Kα/Cr Kα for the Pb type, and Zr Kα/Bi Lα and Cu Kα/Crα for the Bi type, respectively. The samples were compared with other elements detected by pXRF to further discriminate them. 98.9% of all pairs were successfully discriminated. Results showed that black ceramic prints on automotive glasses are able to be discriminated by pXRF.
查看更多>>摘要：Abstract Presently, investigations of drug‐facilitated crimes (DFCs) rely on the detection of substances extracted from biological samples following intake by the victim. However, such detection requires rapid sampling and analysis prior to metabolism and elimination of the drugs from the body. In cases of suspected DFCs, drug‐spiked beverage samples, whether in liquid, droplet, or even dried form, can be tested for the presence of spike drugs and used as evidence for the occurrence of DFCs. This study aimed to quantitatively determine three sedative‐hypnotics (ketamine, nimetazepam, and xylazine) from drug‐spiked beverages using a vortex‐assisted dispersive liquid–liquid microextraction‐gas chromatography (VADLLME‐GC) approach. In this study, a GC method was first developed and validated, followed by the optimization of the VADLLME protocol, which was then applied to quantify the target substances in simulated forensic case scenarios. The developed GC method was selective, sensitive (limit of detection: 0.08?μg/ml [ketamine]; 0.16?μg/ml [nimetazepam]; 0.08?μg/ml [xylazine]), linear (R2?>?0.99), precise (%RSD <7.2%), and accurate (% recovery: 92.8%–103.5%). Higher recoveries were achieved for the three drugs from beverage samples in liquid form (51%–97%) as compared to droplet (48%–96%) and dried (44%–93%) residues. The recovery was not hindered by very low volumes of spiked beverage and dried residues. In conclusion, the developed VADLLME‐GC method successfully recovered ketamine, nimetazepam, and xylazine from spiked beverages that are likely to be encountered during forensic investigation of DFCs.
查看更多>>摘要：Abstract The increasing volume, variety, velocity, distribution, structural intricacy, and complexity of use of digital evidence can make it difficult for practitioners to find and understand the most forensically useful information (Casey E. Digital evidence and computer crime: Forensic science, computers, and the Internet. Academic Press; 2011. p. 31; Pollitt M. The hermeneutics of the hard drive: Using narratology, natural language processing, and knowledge management to improve the effectiveness of the digital forensic process [PhD dissertation]. University of Central Florida; 2011). Digital forensic practitioners currently search for information and solutions in an ad hoc manner, leading to results that are unstructured, unverified, and sometimes incomplete. As a result, certain digital evidence is being missed or misinterpreted. To mitigate risks of knowledge gaps, there is a pressing need for a systematic mechanism that practitioners can use to codify and combine their collective knowledge. This work presents the design and development of a solution that catalogs crowdsourced knowledge of digital forensic artifacts in a well‐structured, easily searchable form to support efficient and automated extraction of pertinent information, improving availability and reliability of interpretation of artifacts (general acceptance). Technical implementation and artifact curation are discussed with illustrative examples and recommendations for future work.
NSTL
Wiley