Development of a methodology for the standardisation and improvement of 'Smartphone' photography of patterned bruises and other cutaneous injuries

Human bite-mark analyses can play a prominent role in forensic case investigations, including those involving sexual assault. High-quality photographs routinely secure a link between a bite-mark and an individual's dentition. Access to around the clock forensic photography, however, is often limited, resulting in delay and/or missed opportunities to record valuable evidence. The emergence of Smartphone high-quality photographic technology now provides a previously unimagined opportunity to gather timely forensic photographic evidence. Problems can arise, however, due to the relatively poor quality of the photographs, as a result of many of those taking photographs having received little or no forensic photography training. This study compares unassisted photography with assisted photography, by a specifically developed camera application (App), to provide a standardised method for taking forensic photographs. An App, written in Java, was hosted on the Google Android Operating System, on a Samsung Galaxy SII Smartphone. Twenty-four volunteers participated in a study to photograph a pseudo bite-mark using three methods, (1) unassisted (as a control), (2) assisted by an ABFO No.2 right-angled photographic reference scale and (3) assisted by the App. The App, method (3), was shown to consistently outperform methods (1) and (2), demonstrating greater standardisation and precision (p<0.001). Analysis of the data showed the extent to which acquiring an accurate photograph depends on the image being orthogonal to the camera. It appears likely that the relatively inaccurate photographs acquired by methods (1) and (2), were as a result of deviation from the plane, orthogonal to the bite-mark. Therefore, the App was successful in ensuring that the camera was both orthogonal and at an appropriate distance, relative to the bite-mark. Thus, the App enhanced the abilities of non-experts to acquire more accurate photographs and created the potential to significantly improve the quality of forensic photographs.

Comparison of simulated human dermal bitemarks possessing three-dimensional attributes to suspected biters using a proprietary three-dimensional comparison

The infliction of a bite is a four-dimensional space-time event that is ideally analyzed with three-dimensional (3-D) technology. Comparison of 2-D images (photographs) of a bitemark with a 3-D replica of a suspect's dentition is challenging. The authors present a technique that produces 3-D images of indented marks and dentitions for comparisons. Study models and corresponding dental-wax bites were digitized by 3-D scanning, and comparison overlays were generated using DentalPrint software. The effectiveness of the method was analyzed by determining the area under receiver operating characteristic (ROC) curve and the sensitivity, specificity and 95% confidence interval (CI) for each cut-off point. An area under the ROC curve of 0.953 (SE=0.029; 95% CI=0.893-0.985) and high sensitivity and specificity values were obtained for 104 comparisons made by an expert examiner, who correctly identified 92.3% of matching dentitions and 98.7% of non-matching dentitions. This technique can be considered a highly accurate method of bitemark analysis, although indentations must be present in the injury, limiting the cases that can be resolved. A comparative study of the same dentitions using 2-D bitemark photography confirmed the superiority of the new approach.

A forensic classification of distortion in human bite marks

The occurrence of distortion in human bite marks is well recognised. A forensic classification of distortion is suggested which is based upon the causative factors and their inter-relationships. The terms primary distortion and secondary distortion are introduced and described. The objective of this classification is to emphasise the need for a scientific approach to the recognition and interpretation of the types of distortion found in human bite marks. The relationships between distortion, distinctive features and superimposition techniques in bite mark analysis are discussed.

Bite marks in forensic dentistry: a review of legal, scientific issues

Bite marks are an important and sometimes controversial aspect of forensic odontology. The discipline has recently received considerable attention in the media and in scientific realms. Although there are many cases in which bite mark evidence has been critical to the conviction or exoneration of criminal defendants, there is continuing dispute over its interpretation and analysis. This article explores the legal and scientific basis of bite mark evidence.