A reliable and robust laboratory method is essential for the forensic analysis of deoxyribonucleic acid (DNA), particularly for low-template samples. Electropherogram peak heights are important to the identification of STR alleles, and these peak heights are prone to error. Since error can be introduced into the process during sample preparation, quantification, amplification, or analysis, validation studies are performed in an attempt to characterize the signal variation associated with the process. While current practices assess aspects of a method, such as sensitivity and reproducibility, the effects of daily laboratory alterations are often not considered. Additionally, samples used in a validation study may be prepared using serial dilutions. Therefore, understanding the extent to which error is propagated through the series and the effect it has on the results could help improve validation practices. This work aimed to assess the effect daily laboratory modifications have on the signal in a forensic electropherogram. Specifically, the variability in signal when different capillary and amplification kit lots were used was evaluated against the variability observed when a single sample was either injected or amplified multiple times. The variability was determined via the examination of peak heights, peak height ratios, stutter, and drop-out. The effect of serially diluting samples was examined via an in silico model of the dilution process, polymerase chain reaction (PCR), and capillary injection. The peak heights from simulated serially diluted samples using the concentration of a stock DNA were compared to the peak heights from simulated samples that were quantified after the dilution series was generated and prior to amplification. The different capillary lots and amplifications were found to result in greater variation compared to the multiple injections. Additionally, when the stutter percentages obtained from using multiple kit lots were compared to those obtained using the same kit lot, differences in stutter percentage deviations resulted in different stutter thresholds. Drop-out rates were also different between the samples amplified with one kit versus the same samples amplified with multiple kit lots. Therefore, at a minimum, multiple amplifications should be run on multiple capillary lots during validation. Further, if available, the use of multiple kit lots is recommended, particularly in cases where stutter thresholds or drop-out models are used during interpretation. Creating validation samples via serial dilutions was also found to increase the variation observed in peak height in the simulated samples, suggesting that samples should be quantified post-dilution. In addition to characterizing the variability of several components of DNA analysis, an alternative quantification method was investigated in order to decrease the overall variability associated with the quantification process. This work sought to develop an electrochemical biosensor using a single-stranded DNA (ssDNA) probe chemically adsorbed to a gold electrode. This would allow for the direct quantification of DNA and eliminate the need for qPCR and fluorescent-based oligonucleotide detection systems. The DNA probe was successfully adsorbed to the surface of the gold disk electrode, hybridized to a single-stranded complementary DNA sequence, and detected using square wave voltammetry. Additionally, the ability to control the amount of DNA chemisorbed to the electrode surface was investigated by varying the incubation time in the probe solution. The measured current increased as the incubation time increased from 15 minutes to one hour, after which it plateaued. The use of an electrochemical biosensor is a promising alternative to qPCR for the quantification of DNA, with one hour being the optimal incubation time in the probe solution.

This research paper discusses the role of virtual environments in digital forensic investigations. With virtual environments becoming more prevalent as an analysis tool in digital forensic investigations, it’s becoming more important for digital forensic investigators to understand the limitation and strengths of virtual machines. The study aims to expose limitations within commercial closed source virtual machines and open source virtual machines. The study provides a brief overview of history digital forensic investigations and virtual environments, and concludes with an experiment with four common open and closed source virtual machines; the effects of the virtual machines on the host machine as well as the performance of the virtual machine itself. My findings discovered that while the open source tools provided more control and freedom to the operator, the closed source tools were more stable and consistent in their operation. The significance of these findings can be further researched by applying them in the context of exemplifying reliability of forensic techniques when presented as analysis tool used in litigation.

Biological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in routine forensic casework, RNA of sufficient quantity and quality must be obtained from biological fluid stains and the methods used for RNA analysis must be fully compatible with current DNA analysis methodologies. Several DNA/RNA co-extraction methods were evaluated based on the quantity and quality of DNA and RNA recovered and were also compared to standard non-co-extraction methods. The two most promising methods, the in-house developed NCFS co-extraction and the commercially available AllPrep DNA/RNA Mini kit, were then optimized by improving nucleic acid recovery and consistency of CE (capillary electrophoresis) detection results. The sensitivity of the two methods was also evaluated, and DNA and RNA profiles could be obtained for the lowest amount of blood (0.2 µL) and saliva and semen (1 µL) tested. Both extraction methods were found to be acceptable for use with forensic samples, and the ability to obtain full DNA profiles was not hindered by the co-extraction of RNA. It is generally believed that RNA is less stable than DNA which may prevent its use in forensic casework. However, the degradation rates of DNA and RNA in the same biological fluid stain have not been directly compared. To determine the relative stability of DNA and RNA, the optimized NCFS co-extraction protocol was used to isolate DNA and RNA from iv environmentally compromised stains. Dried blood, saliva, and semen stains and vaginal secretions swabs were incubated at set temperatures and outside for up to 1 year. Even at 56°C, DNA and RNA were both stable out to 1 year in the blood and semen stains, out to 3 months (DNA) and 1 year (RNA) in the saliva stains, and out to 6 months (DNA) and 3 months (RNA) in the vaginal secretions swabs. The recoverability of both nucleic acids was reduced when the samples were exposed to increased humidity, sunlight, and rain. In general, DNA and RNA stability was found to be similar with a loss in ability to obtain a DNA or RNA profile occurring at the same time point; however, there were instances where RNA body fluid markers were detected when a poor/no DNA profile was obtained, indicating that RNA in dried stains is sufficiently stable for mRNA body fluid typing to be used in forensic casework.

No / Forensic archaeology is mostly defined as the use of archaeological methods and principles within a legal context. However, such a definition only covers one aspect of forensic archaeology and misses the full potential this discipline has to offer. This volume is unique in that it contains 57 chapters from experienced forensic archaeological practitioners working in different countries, intergovernmental organisations or NGO’s. It shows that the practice of forensic archaeology varies worldwide as a result of diverse historical, educational, legal and judicial backgrounds. The chapters in this volume will be an invaluable reference to (forensic) archaeologists, forensic anthropologists, humanitarian and human rights workers, forensic scientists, police officers, professionals working in criminal justice systems and all other individuals who are interested in the potential forensic archaeology has to offer at scenes of crime or places of incident. This volume promotes the development of forensic archaeology worldwide. In addition, it proposes an interpretative framework that is grounded in archaeological theory and methodology, integrating affiliated behavioural and forensic sciences.

No description available.

No description available.

DNA samples are a part of the collected physical evidence during the comtemporary crime scene investigation procedure. After processing the samples, a laboratory obtains short tandem repeat electropherograms. In case of mixed DNA profiles, i.e., profiles that contain DNA material from more than one contributor, the laboratory needs to estimate the test statistic (likelihood ratio) that could provide evidence, either inculpatory or exculpatory, against the person of interest. This is automated with probabilistic genotyping (PG) software with (fully-)continuous models: the ones that consider the heights of the observed peaks. In this thesis, we provide understanding of the modern PG methods. We then show how to improve measurable indicators of the algorithm performance, such as precision and inference runtime, that directly correspond to the efficiency and efficacy of work performed in a lab. With quicker algorithms the forensics laboratories can process more samples and provide more comprehensive results by reanalysing the mixtures with different hypotheses and hyperparameterisations. With more precise algorithms, there will be a grater confidence in their results. The precision of the solution would ameliorate the admissibility of the provided evidence and reliability of the results. We achieve improvements over the state-of-the-art by utilising probabilistic programming and modern Bayesian inference methods. We describe a differentiable (and hence continuous) continuous model that can be used with different estimators from both the sampling and variational families of techniques. Finally, as the different PG products output different likelihood ratios, we provide explanation of some of the factors causing this behaviour. This is of high importance because if two solutions are used for the same crime case, the difference must be understood. Otherwise, because of lack of consensus, the results would cause confusion or, in the worst case, would not be admitted by the court.

This project constitutes an instructional unit for honors biology that involves the use of science in the field of criminal investigation and forensics. Before beginning the unit, the learners should have mastered basic laboratory skills, including use of the microscope. They should also have an understanding of the basic structure and function of DNA and its role in heredity and protein synthesis. The standard time frame is 24 days with 70-minute periods, but can be easily adjusted to meet classroom needs. Several instructional strategies enhance student learning and make science fun. The unit is inquiry-driven and activity-based. Students are surprised by the crime, gather and analyze evidence, and work towards proposing an explanation. This real world problem involves the use of cooperative learning and a variety of assessment techniques.

D.Phil.

Esta tese é composta por três capítulos. O primeiro capítulo teve por objetivo analisar quais as técnicas de reconstrução nasal mais consistentes em contexto forense através de uma revisão sistemática da literatura. No total, existem 15 métodos de reconstrução nasal descritos na literatura. Para localizar a ponta do nariz e estimar a projeção nasal em indivíduos brasileiros, o método que se demonstrou, em meta-análise, o mais apropriado foi o que considera que o ângulo (ponto Pronasale) formado pelas retas que partem dos pontos Rhinion e Prosthion possui valor aproximado de 90º. O capítulo II teve como propósito testar, mediante análise de imagens tomográficas, o método desenvolvido em indivíduos brasileiros para estimar a localização da ponta do nariz em casos de reconstrução facial forense. De acordo com a técnica, o ângulo (ponta do nariz) formado pela união de retas traçadas a partir dos pontos Rhinion e Prosthion corresponde a 90º. O programa Horos® foi utilizado para analisar as imagens dos exames de tomografia computadorizada de feixe cônico. Os critérios de seleção da amostra foram semelhantes aos utilizados no trabalho que propõe o método, assim como as análises realizadas. Os resultados mostraram que o ângulo de interesse correspondeu em média a 96.5º. Esta diferença resultou em uma inacurácia de aproximadamente 3 mm da localização estimada da ponta do nariz em relação à sua localização real. Em termos práticos, esta diferença não impede o reconhecimento facial. O terceiro capítulo teve o propósito de testar o método proposto para estimar a largura nasal de indivíduos brasileiros em reconstrução facial forense, além de determinar parâmetros em tecido duro para estimar a largura nasal e verificar relações entre o tipo facial e a morfologia do perfil nasal. A amostra foi composta por 246 imagens de tomografia computadorizada de feixe cônico (feminino: 183; masculino: 63). O programa Horos® foi utilizado. As análises em tecido duro foram realizadas na visualização de reconstrução multiplanar com projeção de máxima intensidade igual a zero, e a análise do perfil nasal foi realizada em tecido mole na ferramenta de visualização de superfícies. Os resultados mostram que o método proposto para estimar a largura nasal em brasileiros apresentou uma inacurácia de aproximadamente 1 mm, fato que não interfere no reconhecimento facial. Não houve relação de proporção direta entre a largura do nariz e a abertura piriforme, nem entre a largura do nariz e a distância intercanina, mesmo quando foram consideradas variáveis como sexo, idade e tipo facial. O biótipo facial longo apresentou relação moderada com o perfil nasal reto (r=0.037). / This thesis contains three chapters. The first chapter aimed to conduct a systematic review to analyze what are the most consistent techniques of nasal reconstruction in a forensic context. There are fifteen nasal reconstruction methods described in the literature. To predict the Pronasale point and the nasal projection, the method that considers that the confluence between the lines traced from Rhinion and from Prosthion is an angle (Pronasale point) with a value of 90º presented good results when meta-analysis was performed. The aim of the second chapter was to test, trough CT images, the method developed on a sample of Brazilian subjects to predict the Pronasale point in forensic facial reconstruction. According to this technique, the union of the Rhinion and the Prosthion lines creates an 90º angle (Pronasale point). The software Horos® was used in order to perform the analysis on the cone-beam tomography images. The inclusion criteria of the sample were the same used by the primary study as well as the performed analysis. The results showed a mean value of 96.5º from the projection Pronasale and Rhinion. This difference results in an inaccuracy of approximate 3 mm of the Pronasale point and it is not impeditive for facial recognition of a familiar face. The third chapter aimed to test the method proposed to predict nasal length in Brazilian subjects, to determine hard tissue parameters to predict nasal length and to observe if there was any relation between facial pattern and nasal profile. The sample was composed by 246 cone beam computed tomography (183 female, 63 male). The software Horos® was used. The hard tissue analysis were performed on 3D multiplanar reconstruction with maximum intensity projection equal to zero, and the 3D surface rendering was used to verify the nasal profile in soft tissue. The proposed method to predict nasal length presented an inaccuracy of approximate 1 mm and it certainly does not influence facial recognition of familiar faces. There was no relation between nor nasal length and piriform aperture nor nasal length and intercanine distance even when sex, age and facial type were considered. The long facial type showed moderate relation with strength nasal profile (r=0.037).