An Integrated Technique for the Analysis of Skin Bite Marks

Abstract

Abstract:The high number of murder, rape, and child abuse cases in South Africa has led to increased numbers of bite mark cases being heard in high courts. Objective analysis to match perpetrators to bite marks at crime scenes must be able to withstand vigorous crossexamination to be of value in conviction of perpetrators. An analysis technique is described in four stages, namely determination of the mark to be a human bite mark, pattern association analysis, metric analysis and comparison with the population data, and illustrated by a real case study. New and accepted techniques are combined to determine the likelihood ratio of guilt expressed as one of a range of conclusions described in the paper. Each stage of the analysis adds to the confirmation (or rejection) of concordance between the dental features present on the victim and the dentition of the suspect. The results illustrate identification to a high degree of certainty.

The individualisation of a dog bite mark: a case study highlighting the bite mark analysis, with emphasis on differences between dog and human bite marks

“…The description of the analysis and individualisation for bite marks is based on the analysis technique described by Bernitz et al [14]. For purposes of this paper, a dog bite mark will be defined as any break in the skin caused by a dog's teeth, regardless of the intention [19].…”

“…There are several papers which describe the procedures to be followed when examining bite marks [2,[12][13][14][15][16], but they do not include protocols to be followed when examining tooth puncture wounds and claw scratch marks commonly experienced in dog attacks. Very little has been published on the individualisation of dog bite marks, distinguishing bite marks from claw marks and the methodologies involved in the above procedures.…”

The application of affine transformations in matching distorted forensic samples with a common origin

“…The practice of forensic odontology regularly requires the expert to establish a degree of concordance between two objects one or both of which have undergone minimal degrees of deformation [1][2][3][4]. For the purposes of this paper, deformation will include warping, shrinkage and distortion.…”

“…The deformation can be the result of a time delay, postural change [4,5], poor photographic technique or physical changes to the evidence [2,6]. These comparisons can be between the dentition of a suspect/ victim and bite marks on inanimate objects/skin [1,3], two radiological images [7], palatal rugae patterns [8][9][10], dental arches, lip prints [8,11] and other unique situations which are presented in forensic odontological cases.…”

“…Any attempt at metrically analysing evidence which is known to have undergone deformations will have negative consequences for the expert witness under cross examination in court [1]. It is not possible for any expert witness to quantify the degree of deformation, and thus impossible to justify a metric comparison of any such evidence irrespective of the deformation present [5].…”