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Problem-based analysis of bitemark misidentifications: the role of DNA. Bowers CM. The dental literature concerning bitemark methodology is surprisingly thin and sorely lacking in rigorous scientific testing. Contra to this fact, the bitemark legal caselaw is surprisingly strong and is used as a substitute for reliability testing of bite mark identification. In short, the Judiciary and the Prosecutors have loved forensic odontologists. This paper will focus on the author's participation as a Defense expert over the last seven years in over 50 bitemark prosecutions and judicial appeals. This sampling will act as an anecdotal survey of actual bitemark evidence. Certain trends regarding methods and reliability issues of odontologists will be discussed. Several of these cases have been later judicially overturned due to DNA analyses after the defendants were originally convicted. These diagnostic misadventures are being vocally discussed in the US media by news and legal investigators who are asking hard questions. The forensic dentistry community, however, is curiously silent. What actions are necessary by the profession to improve this assault on the 52-year tradition of bite mark identifications in the United States? Photographic evidence protocol: the use of digital imaging methods to rectify angular distortion and create life size reproductions of bite mark evidence. J Forensic Sci. 2002 Jan;47(1):178-85. Bowers CM, Johansen RJ. Bite mark evidence seen in skin injuries or objects is commonly photographed for evidentiary documentation, preservation, and analysis. Distortion in forensic evidence photographs diminishes the outcome of analytical procedures available to the forensic odontologist. Inaccurate positioning of the evidence, camera, or measurement reference scale creates perspective and parallax distortion of the captured image. These variables must be eliminated, if possible, to ensure reliable results derived from comparison of the suspect teeth and the bite mark. Detection and measurement of camera/evidence/scale misalignment is the threshold step in evidence evaluation, and is possible through digital imaging methods coupled with established methods. Correction (rectification) of perspective distortion is possible through the application of additional digital editing techniques. This study establishes type categories of perspective and parallax distortion seen in bite mark evidence, validates the use of the digital imaging tools of Adobe Photoshop to correct certain types of distortion, and establishes a forensic protocol to verify the accuracy of evidence photographs requiring dimensional accuracy. Digital imaging methods as an aid in dental identification of human remains. J Forensic Sci. 2002 Mar;47(2):354-9. Bowers CM, Johansen RJ. The physical comparison of known (K) and questioned (Q) evidence samples is an accepted tool in numerous forensic identification disciplines (1). A subset of this process is the use of antemortem and postmortem dental radiographs to identify unidentified human remains. This method has been generally accepted for decades (2). The outcome is performed with a considerable degree of accuracy, due in part to a finite pool of possible candidates for identification derived via the NCIC database, passenger lists, and law enforcement Missing Persons reports. This paper describes a dental identification comparison protocol that incorporated digital imaging technology in this process. The computer was used to create digital exemplars of the K and Q evidence that were spatially and quantitatively compared (3). The digital mode allowed direct metric and morphologic comparison through the aid of a digital camera, desktop computer, monitor, and printer. The well-known computer program Adobe Photoshop 5.0 (4) was used to process the digital information in two forensic cases described in this paper. It is a commercially available digital imaging editing program that is operated on laptop and desktop computers possessing sufficient chip speed and RAM (Pentium II or equivalent and at least 76MB RAM) to open the large-size files generated by high-resolution digital capture devices. This program accepts raster-based image formats (e.g. .JPG, .BMP). Photoshop is noted for its diverse imaging functions, which allow the computer monitor to be used as a comparison microscope when Q and K sample images are tiled side-by-side and/or superimposed. Two and three-dimensional Q and K evidence samples can be individually digitized and then independently resized to allow two-dimensional comparison. The investigator also has the ability to create magnified images (200% to 300%) when the original digital image has been captured at near photoquality resolution (300 dpi). The visual comparison of physical features on the computer monitor permits a large field of view and robust digital control over image quality. Photographic measurement and enhancement features of Adobe Photoshop mimics and in some circumstances surpasses the historic use of conventional photographic manipulation in forensic casework. This paper presents two cases processed via routine forensic odontology identification protocols. These protocols had minimal results due to limitations described in the case histories. The additional application of digital methods proved useful in the ultimate identification of these human remains. Accuracy of bite mark overlays: a comparison of five common methods to produce exemplars from a suspect's dentition. J Forensic Sci. 1998 Mar;43(2):362-7. Sweet D, Bowers CM. Physical comparison of a suspect's teeth to a bite mark injury using hollow volume comparison overlays is a common forensic odontology technique. Several methods are used to record characteristics of the size, shape and position of the teeth and to generate overlays. These include computer-based, radiographic, xerographic and hand-traced methods. Five common overlay production methods were compared using digital images of dental study casts as a reference standard. Area of the biting edges of the anterior teeth and relative rotation of each anterior tooth were measured and compared. The computer-based production method was determined to be the most accurate of those studied. It produced accurate representations of the biting edges of the teeth in an objective manner. The radiographic method was determined to be more accurate than the xerographic method with respect to tooth area measurement. The opposite is true with respect to tooth rotation. Hand-traced methods, from either wax impressions of teeth or directly from study casts, were determined to be inaccurate and subjective. It is recommended that forensic odontologists discontinue the use of hand-traced overlays in bite mark comparison cases. Radiographic reconstruction of root morphology in skeletonized remains: a case study. J Forensic Sci. 1996 May;41(3):514-7. Law CA, Bowers CM. This is a case study in the application of a laboratory technique first described by Dr. Brion C. Smith in the Journal of Forensic Sciences in January 1992. Our study evaluated a human skull that showed perimortem and/or postmortem tooth loss. It was discovered in 1991 and deemed to have no usable dental information due to severe alveolar bone destruction. In 1994, using minor modifications of Dr. Smith's technique, we sealed off the open tooth sockets and injected a radiopaque material which, after radiographic analysis, revealed previously unobserved dental information. This report demonstrates that root morphology can be reconstructed. This yields radiographic information that may be useful in the identification of unknown human remains. Jurisprudence issues in forensic odontology. Dent Clin North Am. 2001 Apr;45(2):399-415, ix. Bowers CM. This article exposes the dental profession in the legal environment and the rules that control the acceptance or rejection of expert witness testimony. Written by a practicing dentist and attorney, the author believes that the new forensic dentistry aspirant should develop mentoring relationships with more experienced medico-legal professionals to supplement traditional dental education.

Related Books

Forensic Dental Evidence: An Investigator's Handbook This handbook is written for police investigators and forensic personnel who are tasked with developing investigations that require expertise in dentistry. The focus is providing the information necessary to recognize and professionally manage dental evidence. Investigators will understand the scientific nomenclature, scientific issues and the specialized forensic nature of this type of forensic investigation. The emphasis is on human identification from dental structures, the identification of people from bite marks, and the signs and significance of dental injuries present in violent crime.

Bitemark Evidence The first stand-alone textbook on the subject, this reference compiles the expertise and recommendations of a team of 21 eminent specialists from the disciplines of forensic odontology, DNA analysis, pathology, and jurisprudence to illustrate the many facets of bitemark recognition, diagnosis, handling, excision, lifting, transillumination, storage, preservation, transportation, analysis, and comparison. With more than 543 black and white photographs and 32 full-color pages, the book illustrates animal and human bitemarks on the living, the deceased, and on objects, incorporating sections on the history of bitemark evidence, salivary DNA, genotypic comparison of oral bacteria, and more. Bloodstain Pattern Analysis

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