Classification System for Bitemark Evidence - Case Study Example

ification System for Bite-mark Evidence Bite-mark evidence tends to become controversial due to non-standard methods of assessment, ification, documentation and presentation. There are many recorded cases of erroneous convictions based on bite-mark evidence. On the other hand, it is equally likely that many criminals go unpunished due to improper recording of bite-mark evidence. Therefore, bite-mark evidence alone came to be considered unreliable and incapable of securing conviction independently. Proper classification of bite-mark evidence is, therefore, crucial in removing some of the elements of doubt about it. Bite-marks are defined as physical alterations in a medium caused by the contact of teeth or representative patterns left in an object or tissue by the dental structures of an animal or human. (Bowers). Bite-marks are inflicted by a human being for any one or more of three reasons; 1. To derive sadistic pleasure 2. As a punishment or to express anger 3. Defensive action, causing infliction on victims and offenders Criminal investigation experts consider bite-mark evidence as effective in individualization as fingerprinting. (www.mincava.umn.edu). Fingerprint sorting and analysis use standard protocols like the Henry Classification System, while bite-mark analysis does not use a standard protocol. Individual experts use their own methods and reasoning, leading to accusations that bite-mark analysis is new and unfounded, with no basis for the uniqueness of human dentition. (http://faculty.ncwc.edu). Human bite-mark analysis largely involves the evaluation of dental bite marks on human flesh, and like any other method of analyzing and interpreting physical evidence, consists of five major activities, namely recognition, identification, classification, individualization and reconstruction. Seven types of bite marks have been identified. They are hemorrhages, abrasions, contusions, lacerations, incisions, avulsions and artifacts. They are further classified into four degrees of impression: clearly defined, obviously defined, quite noticeable, and lacerated. Contusions are most common and incisions offer the best three-dimensional image of the biting teeth. (C. Lee) Improvements on existing methods of classification Classification of bite-mark evidence involves recognition, identification, classification and individualization, and leaves only a limited scope for reconstruction. In addition, a bite-mark classification system needs to accommodate an element of subjective interpretation. Standard terminology to convey the intended meaning of subjective interpretation should therefore form a part of the system of classification. The peculiar circumstances that usually result in bite-marks also allow a different kind of interpretation based on previous studies. An obvious example would be to attempt to classify the victim of a bite-mark as either a perpetrator of the crime or victim of a crime based on the location of the bite-mark on the human anatomy. Does a bite-mark on the palm of the hand indicate that the victim of the bite was a perpetrator of the crime? Bite-marks on the breast or buttocks cannot be self inflicted indicate that the bite victim is a victim of the crime too. Classification of bite-mark evidence also needs to accommodate the transient nature of the bite-mark. The bitten surface is in most cases human flesh which either heals or decays in days or even hours, with almost all bite-marks changing with time. Thus the classification system should also incorporate a temporal aspect in the documentation. Thus a classification system for bite-mark evidence for use in conducting forensic examinations must be based on: 1. Statement of the degree of confidence that the injury is a bite-mark – possible, probable or definite. 2. Anatomical location of the bite-mark – specific location on arm, breast, face or any other part, offering clues about the role of the bite victim in the crime. 3. Anatomical Orientation of the Bite-mark – identification of relative positions of upper and lower teeth causing the bite-mark. 4. Visual inspection of the bite-mark – a) Is it a human or animal bite-mark? b) Characteristics of the surface having the bite-mark and possibility of distortion– resilient, hard, elastic etc (Brooks S) 5. Photographic and forensic identification findings from the original autopsy photograph. The determination of which teeth made specific marks, based on Tooth Class Characteristics. Front teeth are the primary biting teeth in bite-marks, and the six upper front teeth and six lower front teeth are different in shape among themselves. The upper jaw is wider than the lower jaw. 6. Bite Mark Characteristics: The upper 4 front teeth make rectangular marks, the central being wider than the laterals. The upper cuspids make round or ovoid marks. Gaps appear between marks appear due to missing and shorter teeth, or if the tooth or teeth were blocked from impacting the skin. 7. The forensic identification value of the bite-mark injury classified as high, low, weak, or slight depending on the presence of any extraordinary dental features in the injury. 8. The accuracy of the photograph of the bite-mark and the extent of parallax distortion 9. Comparison of the bite-mark with the suspect’s teeth using spatially compared computer prints of each bite-mark region and overlays. 10. Bite site evidence like saliva swabs and photographic documentation of the bite site 11. Impressions of the bite site 12. Dental records of suspects 13. Victims dental impressions. They are particularly useful if the victim had bitten the assailant and the bite site is accessible to the victims dentition 14. Documentation and recording comprising of: Age, race and sex of the victim, surface contour-whether flat, curved or irregular, tissue characteristics, underlying structure-whether bone, cartilage, muscle, or fat, skin tension – whether relatively fixed or mobile, description of the shape of the bite-mark - e.g. essentially round, ovoid, crescent, irregular, etc, and colour of the bite-mark - e.g. red, purple, etc, dimensions of the bite-mark in both planes, nature of injury-whether contusion, abrasion, laceration or incision, presence of any avulsion or artifact and any other pertinent information 15. Whether appearance and features of the bite-mark were affected by washing, contamination, embalming, healing or decomposition, change of position, etc. 16. Estimated time of occurrence derived from other evidence 17. Impressions of the bite-mark taken using standardized methods and materials. 18. Tissue specimen of the bite-mark 19. Description of the bite-mark using standard terminology - partial, indistinct or faded, superimposed or multiple, unique, distinctive (www.forensic.to/webhome). Though a certain element of subjectivity is unavoidable in bite-mark analysis and classification, proper interweaving of different aspects to arrive at a finding will lessen the impact of any perception of subjectivity. Use of sophisticated digital methods of analysis enhances the effectiveness and credibility of bite-mark evidence. Improper handling at the crime scene and delays in collecting bite-mark evidence can hamper proper recognition, identification and classification of the bite-mark evidence. Creating a better awareness among investigators about the importance of bite-mark evidence, together with proper training in recognition, identification and classification methods can eliminate the chances of risk and make bite-mark evidence crucial in forensic examinations. A classification system that includes all the 19 parameters listed above can make the evidence as effective in individualization as other traditionally accepted evidence types like fingerprint evidence. Works Cited C. Michael Bowers DDS, JD: Diplomat, American Board of Forensic Odontology. Home Page, Mincava: Accessed on 29 November 2006. Home Page, Faculty NCWC Accessed on 29 November 2006. Dr. Henry C. Lee: Advances in Forensic Science: Legal and Ethical Responsibilities. Paper presented by at the Montreal Conference, July 1999. Rawson R D, and Brooks S: Classification of human breast morphology in bite-mark investigation. Home Page Forensic: Accessed on 30 November 2006 Read More