Interest In Forensic Science Research Articles

Rheological behavior of brain tissue: Experiments vs theory and forensic applications

Experimental data describing the uniaxial compression and relaxation of brain tissue are compared to the predictions from a rheological model developed by Yarin and Kosmerl [“Rheology of brain tissue and hydrogels: A novel hyperelastic and viscoelastic model for forensic applications,” Phys. Fluids 35, 101910 (2023)]. A qualitative agreement between the model and experiments with swine brain tissue is confirmed, and the uniformly valid values (i.e., valid in all rheometric experiments without any change) of the rheological parameters are established. These are the values of the following four parameters: G (the shear modulus), κ (the bulk modulus), α (the dimensionless degree of hyperelasticity), and θ (the viscoelastic relaxation time). In addition, the present rheological model with the established rheological parameters is incorporated into a dynamic model of bullet penetration into brain tissue after a short-range shooting, when muzzle gases and/or air fill the bullet channel leading to its widening, wave propagation, fragmentation, and backspatter of brain tissue. This problem is of significant interest in forensic science because there is an urgent need to provide physics-informed models to reconstruct and analyze crime scenes.

Extraction and untargeted analysis of metabolome from undemineralised cortical bone matrix.

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) untargeted metabolomics has become the gold standard for the profiling of low-molecular-weight compounds. Recently, this discipline has raised great interest in forensic sciences, especially in the field of toxicology and for post-mortem interval estimation. The current study aims at evaluating three extraction protocols and two LC-MS/MS assays run in both positive and negative modes, to identify the most suitable method to conduct post-mortem metabolomic profiling of bone tissue. A fragment of the anterior tibia of a 82 years-old male sampled from a human taphonomy facility was powdered via freeze-milling. The powdered sub-samples were extracted in five replicates per protocol. Methods tested were (I) a biphasic chloroform-methanol-water protocol, (II) a single phase methanol-water protocol, and (III) a single phase methanol-acetonitrile-water protocol. LC-MS/MS analyses were carried out via high performance liquid chromatography, either on hydrophilic interaction (HILIC) or on reversed-phase (C18) columns in both positive and negative ionisation modes, coupled with a Q-TOF mass spectrometer. Results suggest that the highest consistency between replicates and quality control samples was obtained with the single phase extractions (i.e., methanol-acetonitrile-water), whilst the ideal combination of instrumental set up HILIC chromatography in positive ionisation mode and of C18 chromatography in negative ionisation mode. For the purpose of forensic investigations, a combination of a single phase extraction and the two aforementioned chromatographic and mass spectrometry modes could represent an ideal set up for obtaining bone metabolomic profiles from taphonomically altered bones.

The devil is in the details: Variable impacts of season, BMI, sampling site temperature, and presence of insects on the post-mortem microbiome.

Post-mortem microbial communities are increasingly investigated as proxy evidence for a variety of factors of interest in forensic science. The reported predictive power of the microbial community to determine aspects of the individual's post-mortem history (e.g., the post-mortem interval) varies substantially among published research. This observed variation is partially driven by the local environment or the individual themselves. In the current study, we investigated the impact of BMI, sex, insect activity, season, repeat sampling, decomposition time, and temperature on the microbial community sampled from donated human remains in San Marcos, TX using a high-throughput gene-fragment metabarcoding approach. In the current study, we investigated the impact of BMI, sex, insect activity, season, repeat sampling, decomposition time, and temperature on the microbial community sampled from donated human remains in San Marcos, TX using a high-throughput gene-fragment metabarcoding approach. We found that season, temperature at the sampling site, BMI, and sex had a significant effect on the post-mortem microbiome, the presence of insects has a homogenizing influence on the total bacterial community, and that community consistency from repeat sampling decreases as the decomposition process progresses. Moreover, we demonstrate the importance of temperature at the site of sampling on the abundance of important diagnostic taxa. The results of this study suggest that while the bacterial community or specific bacterial species may prove to be useful for forensic applications, a clearer understanding of the mechanisms underpinning microbial decomposition will greatly increase the utility of microbial evidence in forensic casework.

High-performance LAMP-based method for human sex identification using Y chromosome-specific genetic markers

Finding fast and cheap strategies for DNA typing and human sample identification is of interest in forensic science. We report a new versatile alternative for molecular sex determination using Y-specific targets (TSPY, TTTY, alphoid regions, and Y-Amelogenin). This system uses an isothermal loop-mediated DNA amplification (LAMP) with a set of 6 primers for each target, designed to improve sensibility and specificity, and reducing detection time to only 45 min. Furthermore, detecting the different targets on the Y chromosome either individually or in combination revealed accurate results. Assay sensitivity was determined with a mixture of human female and male DNA at different concentrations to mimic forensic samples. Single primer sets showed high sensitivity at DNA concentrations ranging from 58.6 to 3.7 pg/µL. When a combined primers set was used, sensitivity yielded a detection as low as 0.1 pg/µL of male DNA, making it 10 times more sensitive than qPCR-DNA quantification kits. Finally, high specificity was observed when tested against 6 domestic species.

Topical Collection “The Rise of Forensic Anthropology and Documented Human Osteological Collections”

The idea behind this Topical Collection derives from the growing interest in forensic sciences, specifically forensic anthropology and the study of human remains, supporting the argument that forensic anthropology has favored interest in Documented Human Osteological Collections (DHOCs) [...]

The Eye in Forensic Medicine: A Narrative Review.

The eye, with its distinctive anatomy, not only reflects a wide variety of diseases in life but also undergoes a myriad of post-mortem changes. Consequently, the eye has long been an area of interest in forensic science, primarily for the estimation of post-mortem interval and therefore the time of death and also for assistance in ascertaining the cause of death. There has been significant progress in the knowledge of ophthalmic forensic science using new technologies which have allowed further possibilities to arise where understanding of this field can assist the forensic pathologist. This review aims to highlight the current knowledge which exists in this field and also to identify important avenues for further investigation. Post-mortem changes of the eye along with its current applications and challenges will be discussed. These include the important areas of post-mortem iris biometrics, pupil size correlation with post-mortem interval, use of point-of-care technology on vitreous humor, and the use of ophthalmic imaging in pediatric abusive head trauma.

Cell survival and DNA damage repair are promoted in the human blood thanatotranscriptome shortly after death

RNA analysis of post-mortem tissues, or thanatotranscriptomics, has become a topic of interest in forensic science due to the essential information it can provide in forensic investigations. Several studies have previously investigated the effect of death on gene transcription, but it has never been conducted with samples of the same individual. For the first time, a longitudinal mRNA expression analysis study was performed with post-mortem human blood samples from individuals with a known time of death. The results reveal that, after death, two clearly differentiated groups of up- and down-regulated genes can be detected. Pathway analysis suggests active processes that promote cell survival and DNA damage repair, rather than passive degradation, are the source of early post-mortem changes of gene expression in blood. In addition, a generalized linear model with an elastic net restriction predicted post-mortem interval with a root mean square error of 4.75 h. In conclusion, we demonstrate that post-mortem gene expression data can be used as biomarkers to estimate the post-mortem interval though further validation using independent sample sets is required before use in forensic casework.

Dissertation Project for the Forensic Science Laboratory: Birch Reduction of Ephedrine and Analysis of Byproducts of Forensic Science Interest

This undergraduate dissertation project was designed to enhance organic and analytical chemistry skills of final year forensic science students. A modified Birch reaction method was employed to synthesize amphetamine from ephedrine and detect the most known byproduct of clandestine manufacture of amphetamines, e.g., 1-(1,4-cyclohexadienyl)-2-methylaminopropane (CMP). The use of this synthetic method led to simultaneous N-demethylation and dehydroxylation of the alkaloid. Harmful liquid ammonia and lithium metal, which are the typical reagents of the classic Birch reaction, were replaced by the safer sodium silica gel stage I (Na-SG-I) and an alcoholic proton source. Liquid chromatography–mass spectrometry (LC-MS) was used to monitor reaction progress and identify starting material, products, and byproducts, whereas proton and carbon nuclear magnetic resonance (1H and 13C NMR) and heteronuclear single-quantum correlation (HSQC) NMR spectroscopy experiments were employed to characterize amphetamine and the parent compound ephedrine. This multiweek project-based learning experience has been running for three years at De Montfort University (DMU), which offers a well-established Forensic Science BSc (Hons) undergraduate course. The students were guided with the help of an academic instructor through a research-like setting delving into synthesis, characterization, and analysis of a drug of abuse and its byproduct. As part of this learning experience, which culminated in a body of work that informed the content of final year dissertations, the students gained useful organic chemistry skills and consolidated previously acquired knowledge in trace analysis. A survey of the dissertations’ final grades and evaluation of end-of-project questionnaires revealed that students responded well to the challenges posed by the organic chemistry aspect of the lab and that the project topic and methods were engaging and very relevant to the forensic science course.

GENE EXPRESSION PATTERN ANALYSIS FOR FORENSIC DIAGNOSIS OF SUDDEN CARDIAC DEATH

Diagnosis of Sudden cardiac death (SCD) is challenging for forensic experts. In the current scenario, genetic analysis is rapidly gaining interest in forensic science. Previous studies are not only limited to using protein markers. In this regard, analysis of mRNA is also a key feature. Analysing mRNA offers insight into the diseases and mechanisms leading to death. It can also be used for forensic diagnostic purposes. This review article takes the help of this methodology to discuss about those mRNA species that can aid in the process of sudden cardiac death (SCD) diagnosis. These are mRNA encoding Heat Shock Protein (HSP), mRNA encoding Hemoglobin A1/2 & B, mRNA encoding Pyruvate Dehydrogenase (PDK4), mRNAs encoding Connexin 43 (Cx43) & Zonula occludens-1 (ZO1), mRNA encoding TNNI3, MYL3, TGFB1, MMP9, VEGFA and mRNA expressing Brain Natriuretic Peptide (BNP).Owing to the difficulty of diagnosing SCD, molecular markers are often developed that can aid in the process. Nowadays, mRNA is showing promising usefulness to supplement the process.
 Keywords: Sudden Cardiac Death, forensic, gene expression

FIELDABLE MASS SPECTROMETRY FOR FORENSIC SCIENCE, HOMELAND SECURITY, AND DEFENSE APPLICATIONS.

Mass spectrometry is commonly used in forensic chemistry laboratories for sensitive, definitive analysis. There have been significant efforts to bring mass spectrometry analysis on-site through the development of ruggedized, fieldable instruments. Testing samples in the field is of particular interest in forensic science, homeland security, and defense applications. In forensic chemistry, testing seized drugs in the field can significantly improve efficiencies in processing of related criminal cases. The screening of passengers and luggage at transportation hubs is a critical need for homeland security for which mass spectrometry is well suited to provide definitive answers with low false positive rates. Mass spectrometry can yield reliable data for military personnel testing sites for potential chemical weapons release. To meet the needs of the forensic and security communities fieldable mass spectrometers based on membrane inlet systems and hybrid gas chromatography systems have been developed and commercialized. More recently developed ambient ionization mass spectrometry methods can eliminate the time, equipment, and expertise associated with sample preparation, and so are especially appealing for on-site analysis. We describe the development of fieldable mass spectrometry systems, with emphasis on commercially available systems that have been deployed for on-site analysis of seized drugs, chemical warfare agents, explosives, and other analytes of interest to the forensic and security communities. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.

Characteristic of costal cartilages calcification in relation to sex and age: A forensic review in Aden population

In recent years, there has been renewed interest in forensic sciences about forensic age and sex estimation in living subjects by means of radiology. Costal cartilage bridges, the sternum and the ribs play a key role in the biomechanics of the chest, and is known to be calcified in local regions with age. This study aims at finding out the patterns of costal cartilage calcification in relation to sex and age, and was conducted on digital thorax X-rays to test the usefulness of some radiological changes in the costal cartilage. A descriptive cross sectional study of 1371 radiographs of chest plates were collected from a Diagnostic Medical Center (DMC) in Aden city / Yemen, during the period January 2017 to December 2018, all data were analyzed for their calcification patterns according to the methods of McCormick et al. The incidence of calcification increased with the advancement of age and the earliest appearance of calcification in costal cartilage was seen at 18-19 years in both sexes but more significantly in females. The tendency of central calcification of cartilage was displayed in females, while the peripheral calcification preferred in males, and the mixed calcification seen in both sexes but more in males. It is safe to conclude that different patterns of calcification at rib cartilage observed in digital radiographs are sex specific, that is to say male subjects predominantly show peripheral pattern and female subjects predominantly show central pattern. Calcification of costal cartilage starts at the age of 18-19 years in both sexes and increases with age.

Evaluation of interferers in sampling materials used in explosive residue analysis by ion chromatography

Analysis of explosive residues is of special interest in forensic science. It can be crucial for investigating acts of terrorism or robberies. Ion Chromatography (IC) is a standard technique used by many forensic labs in these cases. Due to the common nature of many explosives and the inherent dirtiness of samples from explosion scenes, sometimes inconclusive or false positive results are obtained by IC, making the identification of interferers extremely important. One possible source of interferer can be the sampling materials themselves, as investigated in this work. First of all, interferers from forensic swabs and syringe filters were evaluated, as these are commonly employed in explosive residue IC analysis. Among the 6 tested samples, only two syringe filters were considered free of interferers. Significant amounts (>0.2mg/L) of Na+, K+, Mg2+, Ca2+, Cl−, and SO42- were found in all forensic swabs and two syringe filters. Then, some ordinary commercial materials, such as cotton swabs, cotton balls, and cotton discs were also tested, as they are often employed in a forensic routine, also. These also showed significant amounts (>0.2mg/L) of Na+, K+, Cl−, NO3−, and SO42-. However, the total concentration of interferers in ordinary commercial materials was lower than in the forensic swabs. Then the effectiveness of removing interferers by washing sampling (swabs, and cotton balls, rolls and disk) and pre-processing (syringe filters) materials was evaluated. This revealed that the interferers could be removed with at least three washes. The results indicated that the sampling materials used for explosion scene analysis should be carefully addressed in forensic analysis. First, by making a previous analysis of the sampling material, preferably prior to use, to evaluate the presence of interferers to ensure that only material free of interferers is used. When it is not possible to perform a prior analysis of sampling materials, they should be analyzed concomitantly with the samples from the post-blast residue in order to estimate the presence of interferers. This would reduce the risk of false positives. Additionally, when interferers are detected, washing can be employed for more reliable routine analysis. We suggest at least 3 wash cycles. This method could be used for ordinary commercial materials, which are cheap and easily obtained.

The expression of 10 candidate specific microRNA markers for human body fluid identification in animal buccal swabs

MicroRNAs (miRNAs) have been of interest in forensic science for body fluid identification with recent years. However, there is no study investigating the species specificity of miRNA markers by the SYBR Green method. Due to the conservation of miRNAs across species, miRNA markers maybe less species-specific than mRNA markers, and in forensic cases, animal buccal swabs are more likely to appear. Therefore, in this study we addressed the influence of 8 kinds of animal buccal swabs on human saliva, semen, vaginal secretion swabs and blood identification with 10 candidate specific miRNA markers by the SYBR Green quantitative PCR. Our data showed that the expression levels of the candidate specific miRNA markers miR-124a and 372 in the cat, dog, mouse and rabbit buccal swabs were in the same range as the human vaginal secretion swabs; buccal swabs from these animals also showed similar expression levels to human saliva for the candidate specific miRNA markers miR-200c, 205 and 658. These results indicated that biomaterials of buccal swabs from cats, dogs, mice and rabbits may be mistaken for human saliva or human vaginal secretion swabs, both of which could result in false positives for human body fluids. Thus, the interpretation of these miRNA profiles for human body fluid identification can be inaccurate in the presence of these animal buccal swabs. Therefore, we suggested performing species tests before human body identification with miRNA markers.

Touch DNA: The effect of the deposition pressure on the quality of latent fingermarks and STR profiles

Latent fingermarks (FMs) present unique, and sometimes the only, evidence found at a crime scene. Several factors affect their quality, including deposition pressure (DP). Its effect on FM size and quality, and on STR amplification success rate, is an emerging area of interest in forensic science. This study examined 540 FM samples, each consisting of index, middle and ring fingers, deposited by 30 donors on glass, polythene (PE) and paper under a range of weights from 0.1 to 10 kg. Both length and width of FMs increased with the increasing DP. FMs deposited under lower (≤0.5 kg) DPs varied in size (p < 0.01), while those deposited at higher (≥3 kg) DPs were more consistent. FM quality on glass and PE, as determined by the AFIS minutiae count and by a fingerprint examiner on a scale from 0 to 4, improved with the increasing DP, but it deteriorated on PE at DP of 10 kg. FM quality on paper continued to improve from DP of 1 kg up to the maximum DP of 10 kg. The effect DP has on the efficacy of DNA profiling from latent FMs was significant as shown by an increase in the DNA amount recovered, the number of amplified loci per FM sample, and the number of forensically useful DNA profiles (defined here as those with ≥8 full STR loci detected) as DP increased. This effect was most pronounced with PE (R = 0.98) and paper (R = 0.96). Altogether, the success rate of DNA profiling varied from 16.3% in FMs deposited on paper to 21.2% and 22.5% of those on PE and glass. The highest number of useful DNA profiles was obtained from glass under DP of 10 kg. Forensically useful FMs obtained at low (≤1 kg) DP from all three substrates significantly outnumbered that of STR profiles, while an opposite, though less pronounced trend, was observed at high (≥3 kg) DP on PE and paper. Application of the simple device for collecting of FMs under controlled pressure designed for this study, and the palm-up mode of FM deposition as described, allowed us to eliminate the undesirable effect of the hand self-weight and to objectively assess the actual effect of increasing DP on FM size and quality, as well as on the efficacy of DNA profiling.

Evaluation of massively parallel sequencing for forensic DNA methylation profiling

Epigenetics is an emerging area of interest in forensic science. DNA methylation, a type of epigenetic modification, can be applied to chronological age estimation, identical twin differentiation and body fluid identification. However, there is not yet an agreed, established methodology for targeted detection and analysis of DNA methylation markers in forensic research. Recently, a massively parallel sequencing-based approach has been suggested. The use of massively parallel sequencing is well established in clinical epigenetics and is emerging as a new technology in the forensic field. This review investigates the potential benefits, limitations, and considerations of this technique for the analysis of DNA methylation in a forensic context. The importance of a robust protocol, regardless of the methodology used, which minimizes potential sources of bias is highlighted.

Identification of individual red blood cells by Raman microspectroscopy for forensic purposes: in search of a limit of detection.

Traces of body fluids can be present at a variety of crime scenes. It is important that forensic investigators have a reliable and nondestructive method of identifying these traces. Of equal importance is establishing the limitations of any method in use, including its detection limit. We have previously reported on the use of Raman microspectroscopy and multivariate data analysis to identify and differentiate body fluids. While many studies use serial dilutions to establish limits of detection, we utilized a different approach and demonstrated that a single red blood cell is sufficient to be correctly identified as blood. The experimental Raman spectra of individual red blood cells were loaded into the previously reported models for body fluid identification, and all were correctly classified as peripheral blood. These results demonstrate that our model can be used to identify peripheral blood, even if there is only a single red blood cell present. Furthermore, a single red blood cell is 5000× smaller than the amount of peripheral blood required to perform DNA analysis in a modern crime laboratory. This means that if a bloodstain is large enough for DNA analysis, Raman microspectroscopy should be able to make a positive identification. Considering that the sample analysis reported here was carried out with a different instrument, not the one used for the previously reported method development, these results also represent a form of method validation. The model's ability to correctly classify spectra acquired on a different instrumental platform is crucial in preparing it for practical application. Graphical Abstract Peripheral blood is of great interest in forensic sciences. While many tests are available for the identification of peripheral blood at a crime scene, most are presumptive and destructive. Here we present results that show our new, nondestructive method can identify peripheral blood using as little as a single red blood cell.

Suçların Aydınlatılmasında CSI Etkisi

Amaç : Bu araştırma, CSI ve benzeri dizilerin adalet sistemi çalışanlarının tutum ve davranışları ile toplum üzerindeki etkisinin değerlendirilmesini amaçlamaktadır. Bu bağlamda araştırmada bir suçun faili olabilecek kişilere CSI ve benzeri dizilerin ne denli yol gösterici olduğu, adalet mekanizmasının farklı alanlarında çalışanların mesleklerini icra etmeleri sırasında toplumun beklentilerinin ne yönde değiştiği ve bu yapımların adli bilimler konusunda gerçekçi bir tutum sergileyip sergilemedikleri hakkındaki sorulara yanıt aranmıştır.Gereç ve Yöntem : Araştırma, 2011-2012 yıllarında İstanbul’da, adli mekanizmanın çeşitli alanlarında hizmet veren polis, adli bilim/tıp uzmanı, serbest avukat, Ceza Mahkemeleri’nde görevli hakim ve Cumhuriyet Savcısı’ndan oluşan toplam 266 kişiyi kapsayan bir anket çalışması ile gerçekleştirilmiştir. Anket sonucunda elde edilen veriler SPPS (Versiyon 20.0) kullanılarak analiz edilmiş ve değerlendirilmiştir.Bulgular: Araştırmanın bazı önemli sonuçlarına göre; her 2 adli mekanizma çalışanından 1’i CSI dizilerini takip etmektedir. Her 10 katılımcıdan yalnızca 3’ü bu dizilerin mesleki uygulamalarını olumlu etkilediğini düşünürken, anketimizi yanıtlayanların yarısından fazlası söz konusu programların suçlu davranışını değiştirdiğini ve eğitimli failler yarattığı fikrine destek vermişlerdir. Her 2 katılımcıdan 1’i bu dizilerin etkisiyle şüpheli ve sanıkların olay yerinde daha az delil bıraktıklarını düşünmektedir.Sonuç: Suçun aydınlatılmasına yönelik adli bilimsel yöntem ve tekniklerin ekranlarda gerçek dışı bir şekilde izleyiciyle buluşmasının, toplumun adalet mekanizmasından beklentilerini değiştirdiği görülmektedir. Bu bağlamda adalet sistemiyle ilk kez karşı karşıya gelen bir vatandaşın soruşturma ve kovuşturma sürecine dair yanlış algılara sahip olabileceği düşünülmektedir.Anahtar Kelimeler: CSI Etkisi; Olay Yeri İnceleme; Adli Bilimsel Yöntem ve Teknikler

Digital evidence, ‘absence’ of data and ambiguous patterns of reasoning

In this paper we discuss the use of digital data by the Swiss Federal Criminal Court in a recent case of attempted homicide. We use this case to examine drawbacks for the defense when the presentation of scientific evidence is partial, especially when the only perspective mentioned is that of the prosecution. We tackle this discussion at two distinct levels. First, we pursue an essentially non-technical presentation of the topic by drawing parallels between the court's summing up of the case and flawed patterns of reasoning commonly seen in other forensic disciplines, such as DNA and particle traces (e.g., gunshot residues). Then, we propose a formal analysis of the case, using elements of probability and graphical probability models, to justify our main claim that the partial presentation of digital evidence poses a risk to the administration of justice in that it keeps vital information from the defense. We will argue that such practice constitutes a violation of general principles of forensic interpretation as established by forensic science literature and current recommendations by forensic science interest groups (e.g., the European Network of Forensic Science Institutes). Finally, we posit that argument construction and analysis using formal methods can help replace digital evidence appropriately into context and thus support a sound evaluation of the evidence.

Activities for Middle School Students To Sleuth a Chemistry “Whodunit” and Investigate the Scientific Method

The recent increased public interest in forensic science, sparked in part by television shows such as CSI and Bones, presents an opportunity for science educators to engage students in forensic chemistry-themed activities to introduce fundamental concepts, such as the scientific method. In an outreach setting, mysteries were used as a way to engage middle school students to select forensics tests, form hypotheses, make observations while conducting the tests, consider positive and negative controls, and use the results to reach conclusions. Student data shows that the outreach activities generally increase student understanding of the scientific method. These activities have been translated from outreach activities into accessible activities for middle and high school classrooms.

3D-MSCT imaging of bullet trajectory in 3D crime scene reconstruction: Two case reports

Postmortem investigations are increasingly assisted by three-dimensional multi-slice computed tomography (3D-MSCT) and have become more available to forensic pathologists over the past 20years. In cases of ballistic wounds, 3D-MSCT can provide an accurate description of the bullet location, bone fractures and, more interestingly, a clear visual of the intracorporeal trajectory (bullet track). These forensic medical examinations can be combined with tridimensional bullet trajectory reconstructions created by forensic ballistic experts. These case reports present the implementation of tridimensional methods and the results of 3D crime scene reconstruction in two cases. The authors highlight the value of collaborations between police forensic experts and forensic medicine institutes through the incorporation of 3D-MSCT data in a crime scene reconstruction, which is of great interest in forensic science as a clear visual communication tool between experts and the court.