Martin Evison

Bone mineral change during experimental heating: An X-ray scattering investigation

The effects of heating and burning on bone mineral have previously been studied using techniques such as X-ray diffraction (XRD) with the aim of discerning a characteristic signature of crystal change. This would enable a better understanding of alteration to bone mineral during heating, which would in turn impact on the preparation and use of natural bone hydroxyapatite as a biomaterial resource. In addition, this knowledge could prove invaluable in the investigation of burned human remains from forensic and archaeological contexts in cremation and funerary practice. Here we describe a complementary method, small-angle X-ray scattering (SAXS), to determine more accurately the changes to bone crystallite size and shape during an experimental heating regimen. Samples were subjected to controlled heating at 500 degrees C, 700 degrees C, or 900 degrees C for 15 or 45 min. Our results show bone crystallites begin to alter in the first 15 min of heating to 500 degrees C or above. They then appear to stabilise to a temperature-specific thickness and shape with prolonged heating. While the samples heated to lower temperatures or for shorter periods produce XRD traces showing little alteration to the apatite, corresponding information obtained from SAXS shows an early, subtle change in crystal parameters.

Forensic three-dimensional facial reconstruction: historical review and contemporary developments.

Despite varied attempts to achieve standardization in traditional techniques and the promotion of some newly developed ones, facial reconstruction remains on the threshold between art and science. It is the point at which science ends and the medical illustrator takes over that has led to most reservations over this branch of forensic anthropology. The purpose of this paper is to demonstrate that many techniques of facial reconstruction are prima facie questionable and to illustrate some possible solutions to the problems which are currently being explored by the Facial Reconstruction Project at the University of Sheffield (UK). The review includes 15 responses to a questionnaire which was offered to facial reconstruction experts and related specialists. The use of 3D color laser scanning equipment, collection of tissue depth measurements from CT scans and the development of a computer system for 3D forensic facial reconstruction, are described.

EXTRACTION OF SINGLE-COPY NUCLEAR DNA FROM FORENSIC SPECIMENS WITH A VARIETY OF POSTMORTEM HISTORIES

Specimens of human bone, teeth and dried blood spots from 3 months to 91 years old, with a variety of postmortem histories, were used in a comparative study of recovery of single-copy nuclear DNA sequences from forensic material. Sequences of the amelogenin and HLA-DPB1 genes were chosen for their value in sexing and identification. Sequences of the mitochondrial non-coding region V were also amplified to compare the recovery of mitochondrial and single-copy nuclear DNA. A variation of the silica method for DNA extraction was refined for application to the forensic specimens in this sample. Single-copy nuclear DNA was amplified from 100% of recent postoperative bone specimens (n = 6), 80% of forensic teeth and bone specimens (n = 10), 78% of recently extracted teeth (n = 18), 78% of exhumed bone up to 91 years old (n = 37) and 69% of 15 year old bone specimens fixed in 10% formalin (n = 20). Amelogenin sexing was correct in 85% of cases (n = 74) in which the sex of the donor had been recorded. There was no correlation between the age of the specimen and the extent of DNA preservation.

Key Parameters of Face Shape Variation in 3D in a Large Sample

Abstract:  Improvement of methods for evidential facial comparison for the Courts relies on the collection of large databases of facial images that permit the analysis of face shape variation and the development of statistical tools. In this paper, we present a short description and key findings of an anthropometric study of face shape variation in three‐dimensions. We used Statistical Shape Analysis to investigate a large database sample (n = 1968), classified by age and gender. We found that size, shape of the bilateral features and midline contributed successively to overall variation. Face size is associated with age. Sexual dimorphism is evident in size and shape, and shows patterns that affect male and female subjects differently. We anticipate this approach will lend itself to the development of methods for analysis of variation within subject groups and the establishment of the relative uniqueness or abundance of facial measurements within them.

Three-dimensional computer visualization of forensic pathology data.

Despite a decade of use in US courtrooms, it is only recently that forensic computer animations have become an increasingly important form of communication in legal spheres within the United Kingdom. Aims Research at the University of Nottingham has been influential in the critical investigation of forensic computer graphics reconstruction methodologies and techniques and in raising the profile of this novel form of data visualization within the United Kingdom. The case study presented demonstrates research undertaken by Aims Research and the Department of Forensic Pathology at the University of Sheffield, which aims to apply, evaluate, and develop novel 3-dimensional computer graphics (CG) visualization and virtual reality (VR) techniques in the presentation and investigation of forensic information concerning the human body. The inclusion of such visualizations within other CG or VR environments may ultimately provide the potential for alternative exploratory directions, processes, and results within forensic pathology investigations.

Visualising the scene: computer graphics and evidence presentation

In the UK forensic animations are becoming an increasingly important visual aid in courtroom situations, where complex data relating to a sequence of events is being visualised before a general public who may have little or no understanding of established forensic procedure or methodology. This paper will introduce and discuss a spectrum of new technologies that utilise new developments in Computer Graphics (CG) and Virtual Reality (VR) for a range of incident investigation and presentation scenarios.

Heat Induced Changes to Dental Resin Composites: A Reference in Forensic Investigations?*

Abstract:  The objective was to investigate color change and surface damage in dental resin composites exposed to high temperatures over different time intervals for comparative purposes. Samples were prepared using two resins ‐ Z100® (R1) and Charisma ® (R2), heated at the following temperatures: 200°C, 400°C, 600°C, 1000°C, for 15, 30 and 45 min (n = 104 for each resin sample). Color (ΔE*) and brightness (ΔL*) changes were analyzed by spectrophotometry using the CIE L*a*b* system and surface changes by Scanning Electron Microscopy (SEM). R1 showed more intense color changes after heat exposure than R2. ΔL* values were found to be the best parameter for evaluation of light and color change. A biphasic pattern after thermal exposure was detected, from dark brown to light white. SEM showed more intense alterations in R2 than in R1. These results indicate that the parameters observed in both resins are useful as a guide in forensic analyses.

Genetic structure of nomadic Bedouin from Kuwait

Bedouin are traditionally nomadic inhabitants of the Persian Gulf who claim descent from two male lineages: Adnani and Qahtani. We have investigated whether or not this tradition is reflected in the current genetic structure of a sample of 153 Bedouin males from six Kuwaiti tribes, including three tribes from each traditional lineage. Volunteers were genotyped using a panel of autosomal and Y-STRs, and Y-SNPs. The samples clustered with their geographical neighbours in both the autosomal and Y-chromosomal analyses, and showed strong evidence of genetic isolation and drift. Although there was no evidence of segregation into the two male lineages, other aspects of genetic structure were in accord with tradition.

An Exploration of Sample Representativeness in Anthropometric Facial Comparison

Abstract:  Faces are assumed to be unique, but their use in court has remained problematic as no method of comparison with known error rates has been accepted by the scientific community. Rather than relying on the assumed uniqueness of facial features, previous research has been directed at estimations of face shape frequency. Here, the influence of age, sex, and ancestry on variation was investigated. Statistical shape analysis was used to examine the necessity for sub‐divisions in forensic comparisons, using a large sample of facial images on which 30 anthropometric landmark points had been placed in 3D. Results showed a clear pattern of separation of the sexes in all age groups, and in different age groups in men. It was concluded that sub‐division of databases by sex will be necessary in forensic comparisons. Sub‐division by age may be necessary in men (although not necessarily in women), and may be necessary by ancestry.

Forensic Facial Comparison: Issues of Admissibility in the Development of Novel Analytical Technique

Much contemporary debate in forensic science concerns validity and admissibility of scientific evidence in court. In this paper, three current approaches to facial identification—image superimposition, photogrammetry, and morphological analysis—are considered with regard to criteria for scientific evidence in the United States, and England, and Wales. The aim of the paper is to assess the extent to which facial image comparison meets criteria of admissibility in these jurisdictions. The method used is a comparative evaluation of the methods of facial image comparison and their underlying premises against the range of admissibility criteria reported in court rulings and relevant judicial and scientific inquiries in the United States and the United Kingdom. While the techniques of facial image comparison are generally accepted within their practitioner communities, they are not tested, and their error rates are unknown. On that basis, the methods of facial image comparison would appear not to meet the anticipated standards. They are, nevertheless, admitted in court in the United States, and England, and Wales. This paper concludes that further research in science and law will be necessary to more definitively establish admissibility of facial image comparison evidence, as it will for other nascent and novel methods that are potentially influential in court proceedings.