Forensic facial reconstruction using 3-D computer graphics: evaluation and improvement of its reliability in identification

This thesis is concerned with computerised forensic 3-D facial reconstruction as a means of identification and involves the restoration of the face on the skull in an attempt to achieve a close likeness of the individual when alive. The reconstruction process begins with the biological identification of the skeletal remains, (age, sex, ancestry and build). Facial reconstruction is then carried out and essentially works by building the “face” up from the skull using soft tissue thicknesses at specific locations from existing data. However, it is used as a last resort on skeletonised, badly decomposed or mutilated corpses, when no other information is available; even then it is only accepted as corroborative evidence in court. It is performed in the hope that it may stimulate recognition, and consequently narrow the field of identification, allowing other tests to be carried out, such as radiographic and/or dental comparisons, DNA analysis or other means, to establish positive identification. The advantages of the computerised method over the manual clay reconstruction are speed, rapid editing capability, production of images that can be stored and reconstructions repeated at any time if required. Furthermore, in many cases, the original skull instead of a cast or model may be used for reconstruction because the 3-D computerised procedure is rapid and non invasive. However, the most significant advantage of this technique with regard to the aims and objectives of the thesis is that a number of alternative reconstructions may be produced sequentially for the same skull by using different facial templates from the database that meet the anthropological/biological criteria of the skull. The issues addressed by the study and therefore its main aims are: a) evaluation and b) improvement of the reliability of facial reconstruction using 3-D computer graphics. The methodology involved initially digitizing a skull using a low-power laser scanner and a video camera interfaced to a computer. From a database of previously scanned faces, ten facial templates were selected that matched the anthropological criteria of each of the skulls, i.e. age, sex, ancestry and build. Landmarks with their corresponding soft tissue thicknesses were then located and placed on the skull and the equivalent ones on the face. The 3-D computer graphics then reconstructed the face by morphing (warping) the facial template over the skull by matching the corresponding landmarks on the skull and face with the appropriate soft tissue thicknesses at those landmark locations. The soft tissue thicknesses used at their specific landmark locations also matched the anthropological criteria of the skulls, since soft tissue depths are dependent on age, sex, ancestry and build. One of the major problems with any reconstruction which affect its reliability for identification is the uncertainty of the shape of some of the individual characteristics of soft tissue structures such as shape of lips, ears and nose/nasal tip since there is not direct information on the skull regarding the shape of some of these features. In addition, with the laser scanning system, the faces within the database all have closed eyes, because of the potential laser hazard to the eyes. Thus it is necessary to add “opened” eyes, head and facial hair (where appropriate) to give a realistic appearance to the face. The software provides the facility to export a 2-D view in a TIFF or JPEG format from the 3-D reconstructed image. The file can then be imported into a police identi-kit system such as E-FIT™, which allows the addition of features. In this study five skulls of known individuals were used for reconstruction in the manner explained. Ten facial templates which fulfilled the anthropological criteria (age, sex, ancestry and build) for each skull were used for the rebuilding process, thus totalling fifty reconstructions. The study employed a psychological resemblance test (experiment 1) where 20 different assessors, were asked to select in each case study, the best three matches of the ten reconstructions with the ante-mortem photograph of the individual during life. The results from these tests were correlated with a mathematical shape analysis assessment using Procrustes Analysis in which, the skull was compared in turn with each of the ten facial templates of each case study (experiment 2).The ranking of the assessors’ reconstruction choice was correlated with the ranking of the Procrustes Analysis by using Spearman’s Rank Order Correlation. The results indicate that although not statistically significant, it would seem however, that in some of the case studies, the mathematical approach using Procrustes Analysis does seems to capture some perceptual similarity in human observers. Experiment 3, similar to experiment 1, was a further psychological resemblance test, which involved implementing E-Fit features on four of the ten reconstructed images per case study. Assessors were asked to select the closest E-Fit image match with the ante-mortem photograph. Again, results indicated that, although not statistically significant, adding E-Fit feature to the images appears to improve perceptual similarity in human observers, provided, the limitations of adding these characteristics are addressed. Furthermore, there also appears to be good agreement in most of the case studies between the two psychological resemblance tests using the two different sets of assessors in experiment 1 and 3 (reconstruction choice and E-Fit choice, respectively). Further work involving anthropometric comparisons and using two methods of assessment (landmark line matching between images and proportion indices) was also carried out (experiment 4). It was found that matching landmark lines between images appeared to be only of limited value due to the images not being aligned at exactly the same viewpoint and magnification. It should be appreciated that because the thesis was based on recognition and was not an anthropometric study, precise alignment of viewpoints was not a requirement. Hence using the same data from the study, although images were in the frontal view, they were not aligned to the accuracy acceptable for an anthropometric study as there was no requirement to so. It would appear that, although there was some correspondence between the discrepant distances and the first and second ranked reconstructions, no firm conclusions could be drawn from this technique and therefore does not assist in understanding the way observers made their choices. Further tests would need to be carried out (beyond the scope of the thesis) to reach any firm conclusions. Undoubtedly, given the complex nature of the recognition process, it would have been desirable to use reconstructions of persons known to the assessors rather than asking them to assess unfamiliar persons, since it is well established that familiar faces are easier to recognize than those that are unfamiliar to observers. It should be appreciated however, that, although the study was designed in this way for practical and ethical reasons, it nevertheless does not truly reflect the real operational forensic scenario. Furthermore, recognition/matching is a much more complex process and even a reconstructed face which may be generally morphologically similar to the person in life may not capture perceptual similarity in human observers, especially in an unfamiliar scenario. It is not certain that identification will always occur even when the facial reconstruction bears good resemblance to the target individual

Spontaneous bowel perforation due to norovirus: a case report

Norovirus is the leading cause of epidemic gastroenteritis worldwide but the disease is usually self-limiting and generally only causes serious health problems in the young, elderly and immunocompromised. The authors report a case of bowel perforation in an elderly Caucasian lady with confirmed infection with Norovirus genogroup II and no other presumptive cause. To the authors' knowledge this is the first such case of bowel perforation due to Norovirus. Viral gastroenteritis should be considered in the list of differentials when no obvious cause of bowel perforation can be identified to minimise morbidity and mortality

The post-mortem resilience of facial creases and the possibility for use in identification of the dead

The post-mortem resilience of facial creases was studied using donated bodies in order to establish the efficacy of crease analysis for identification of the dead. Creases were studied on normal (pre-embalmed) and bloated (embalmed) cadavers at the Centre for Anatomy and Human Identification (CAHID) to establish whether facial bloating would affect facial crease visibility. Embalming was chosen to simulate the effects produced by post-mortem bloating. The results suggested that creases are resilient and changes were only detected for creases located on the periphery of the face, particularly at areas where the skin is thick, such as at the cheeks. Two new creases not previously classified were identified; these creases were called the vertical superciliary arch line and the lateral nose crease. This research suggests that facial creases may be resilient enough after death to be utilised for human identification

Pseudoaneurysm of the left ventricle following apical approach TAVI

Symptomatic severe aortic stenosis carries a two year survival of only 50%. However many patients are unsuitable for conventional aortic valve replacement as they are considered too high risk due to significant co-morbidities. Transcatheter Aortic Valve Implantation (TAVI) offers a viable alternative for this high risk patient group, either by the femoral or apical route. This article reports a case of a pseudoaneurysm of the left ventricle following an apical approach TAVI in an elderly lady with severe aortic stenosis. To our knowledge pseduoaneuryms of the left ventricle have been reported infrequently in the literature and has yet to be established as a recognised complication of TAVI

Appraisal of traditional and recently proposed relationships between the hard and soft dimensions of the nose in profile

This paper tests six methods of predicting external nasal profile proportions, using the form and dimensions of the bony nasal (piriform) aperture. A sample of 122 lateral cephalograms was measured and traced before each method was attempted, under blind conditions where appropriate. Error was assessed by comparing predicted to actual proportions. Methods used by the following authors were tested: Krogman and Iscan (1986 The Human Skeleton in Forensic Medicine, Springfield: C.C. Thomas), Gerasimov (1955 The Reconstruction of the Face on the Skull), Prokopec and Ubelaker (2002 Forensic Sci. Commun. 4:1–4), Macho (1986 J. Forensic Sci. 31:1391–1403), George (1987 J. Forensic Sci. 32:1305–1330), and Stephan et al. (2003 Am J. Phys. Anthropol. 122:240–250). The two-tangent method by Gerasimov (1955 The Reconstruction of the Face on the Skull) was found to perform best at predicting a point on the nasal tip on male and female preoperative subjects. The method of Krogman and Iscan (1986 The Human Skeleton in Forensic Medicine, Springfield: C.C. Thomas) performed poorly, as did the nasal profile determination method (Prokopec and Ubelaker 2002 Forensic Sci. Commun. 4:1–4). The other methods, all derived by a process of regression calculations, were shown to perform with variable accuracy on this sample, despite the age range and ethnicity of this sample closely resembling that of the samples from which these methods were derived

Hypoxia causes increased monocyte nitric oxide synthesis which is mediated by changes in Dimethylarginine Dimethylaminohydrolase 2 expression in animal and human models of normobaric hypoxia

Tissue hypoxia is a cardinal feature of inflammatory diseases and modulates monocyte function. Nitric oxide is a crucial component of the immune cell response. This study explored the metabolism of the endogenous inhibitor of nitric oxide production asymmetric dimethylarginine(ADMA) by monocyte dimethylarginine dimethylaminohydrolase 2(DDAH2), and the role of this pathway in the regulation of the cellular response and the local environment during hypoxia.Peritoneal macrophages were isolated from a macrophage-specific DDAH2 knockout mouse that we developed and compared with appropriate controls. Cells were exposed to 3% oxygen followed by reoxygenation at 21%. Healthy volunteers underwent an 8 h exposure to normobaric hypoxia with an inspired oxygen percentage of 12%. Peripheral blood mononuclear cells were isolated from blood samples taken before and at the end of this exposure.Intracellular nitrate plus nitrite(NOx) concentration was higher in wild-type murine monocytes after hypoxia and reoxygenation than in normoxia-treated cells (mean(SD) 13·2(2·4) vs 8·1(1·7) pmols/mg protein, p = 0·009). DDAH2 protein was 4·5-fold (SD 1·3) higher than in control cells (p = 0·03). This increase led to a 24% reduction in ADMA concentration, 0·33(0.04) pmols/mg to 0·24(0·03), p = 0·002). DDAH2-deficient murine monocytes demonstrated no increase in nitric oxide production after hypoxic challenge. These findings were recapitulated in a human observational study. Mean plasma NOx concentration was elevated after hypoxic exposure (3·6(1.8)μM vs 6·4(3·2), p = 0·01), which was associated with a reduction in intracellular ADMA in paired samples from 3·6(0.27) pmols/mg protein to 3·15(0·3) (p < 0·01). This finding was associated with a 1·9-fold(0·6) increase in DDAH2 expression over baseline(p = 0·03).This study shows that in both human and murine models of acute hypoxia, increased DDAH2 expression mediates a reduction in intracellular ADMA concentration which in turn leads to elevated nitric oxide concentrations both within the cell and in the local environment. Cells deficient in DDAH2 were unable to mount this response

On the relationships between applied force, photography technique, and the quantification of bruise appearance

Bruising is an injury commonly observed within suspect cases of assault or abuse, yet how a blunt impact initiates bruising and influences its severity is not fully understood. Furthermore, the standard method of documenting a bruise with colour photography is known to have limitations which influence the already subjective analysis of a bruise. This research investigated bruising using a standardised blunt impact, delivered to 18 volunteers. The resulting bruise was imaged using colour, cross polarised (CP) and infrared photography. Timelines of the L*a*b* colour space were determined from both colour and CP images for up to 3 weeks. Overall, no single photographic technique out-performed the others, however CP did provide greater contrast than colour photography. L*a*b* colour space timelines were not attributable any physiological characteristics. Whilst impact force negatively correlated with BMI (R2 = 0.321), neither were associated with any measure of bruise appearance. Due to the inter-subject variability in the bruise response to a controlled infliction, none of the methods in the current study could be used to reliably predict the age of a bruise or the severity of force used in creating a bruise. A more comprehensive approach combining impact characteristics, tissue mechanics, enhanced localised physiological measures and improvements in quantifying bruise appearance is likely to be essential in removing subjectivity from their interpretation

A blind accuracy assessment of computer-modeled forensic facial reconstruction using computed tomography data from live subjects.

A computer modeling system for facial reconstruction has been developed that employs a touch-based application to create anatomically accurate facial models focusing on skeletal detail. This article discusses the advantages and disadvantages of the system and illustrates its accuracy and reliability with a blind study using computed tomography (CT) data of living individuals. Three-dimensional models of the skulls of two white North American adults (one male, one female) were imported into the computer system. Facial reconstructions were produced by two practitioners following the Manchester method. Two posters were produced, each including a face pool of five surface model images and the facial reconstruction. The face pool related to the sex, age, and ethnic group of the target individual and included the surface model image of the target individual. Fifty-two volunteers were asked to choose the face from the face pool that most resembled each reconstruction. Both reconstructions received majority percentage hit rates that were at least 50% greater than any other face in the pool. The combined percentage hit rate was 50% above chance (70%). A quantitative comparison of the facial morphology between the facial reconstructions and the CT scan models of the subjects was carried out using Rapidform(™) 2004 PP2-RF4. The majority of the surfaces of the facial reconstructions showed less than 2.5 mm error and 90% of the male face and 75% of the female face showed less than 5 mm error. Many of the differences between the facial reconstructions and the facial scans were probably the result of positional effects caused during the CT scanning procedure, especially on the female subject who had a fatter face than the male subject. The areas of most facial reconstruction error were at the ears and nasal tip

Anal Examinations in Cases of Alleged Homosexuality

Anal examinations are forcibly conducted in many countries where consensual anal intercourse is considered a criminal act. They are conducted almost exclusively on males in an effort to “prove” that they are “homosexuals” despite the fact that anal intercourse is not a necessary determinant of “homosexual activity.” Forcibly conducted anal examinations are usually initiated at the request of law enforcement officials, the prosecutor, or the court and conducted in the absence of informed consent or in circumstances where individuals are not capable of giving genuine informed consent or where refusal to give consent would be interpreted as self-incrimination. This may be presumed to be the case when examinations are conducted on individuals in detention, subsequent to allegations of criminalised sexual acts by the authorities. The purpose of this medico-legal statement is to provide legal experts, adjudicators, health care professionals, and policymakers, among others, with an understanding of: 1) the validity of forcibly conducted anal examinations as medical and scientific evidence of consensual anal intercourse; 2) the likely physical and psychological consequences of forcibly conducted anal examinations; and 3) whether, based on these effects, forcibly conducted anal examination constitutes cruel, inhuman, or degrading treatment or torture