Expert Disagreement in Bitemark Casework*

Abstract

Bitemark cases continue to raise controversy due to the degree of expert disagreement which is frequently seen. Using a case mix of 49 bitemark cases from 2000 to 2007 each injury was independently assessed for its forensic significance using a previously described bitemark severity scale. Following the assessment, the mean value for the bites was categorized according to the crime type, the degree of expert agreement, and the judicial outcome. Results suggest that bitemarks found in child abuse cases have statistically significantly lower forensic value than those in other crime types, that bites where there is mutual agreement between experts will have higher forensic value than those where there is disagreement at trial, and that cases in which DNA has provided an exoneration will demonstrate similar quality to those where a conviction was secured. Forensic odontologists should carefully assess bitemark evidence and ensure that it meets certain minimums in relation to the presence of class and unique features before undertaking an analysis.

Forensic Odontology

“…Impressions of the suspect made in material similar to that involved in the case were successfully matched to the case patterns. These cases show that it is worth trying bite mark analysis even in cases of bad documentation (Bowers 2006;Bowers and Pretty 2009). 5.…”

“…Another application of this variability is the comparison of bite marks left in violent crimes with specific suspects. The reliability of bite mark comparisons varies based on the evidence substrate and other factors, and cases of incorrect associations have been documented meaning this application requires highly specialised expertise (Bowers 2006;Bowers and Pretty 2009). Wherever possible, DNA testing of the bite mark saliva has replaced this analysis.…”

Is current bite mark analysis a misnomer?

“…In the last decade bite mark analysis has become a highly contentious topic, currently undergoing vigorous review and reevaluation worldwide [1]. Although admissibility of bite mark evidence has been established and routinely accepted in many legal systems for a long time, some odontologists, and perhaps more importantly, lawyers now argue that bite mark methodology has never really undergone sound scientific validation and has never been carefully and critically scrutinised in order to legitimately pass the appropriate tests for admissibility, such as the Frye or Daubert tests as applied in parts of the USA.…”

Ataque mortal por perros de raza rottweiller a una mujer adulta: posible ataque en manada y antropofagia postmortal: Revisión y análisis de un caso de autopsia médico legal

“…Se ha sugerido también que algunas características distintivas de la dentición del animal (rotaciones, malposiciones o ausencias de piezas dentales) pueden reflejarse en las marcas de mordedura. No obstante, algunos recientes trabajos alertan sobre el uso de estas marcas de mordedura con fines de identificación basada en características específicas de la dentición 25,26 . Así, en experimentos sobre mordeduras humanas se ha podido identificar la presencia de falsos positivos a hallazgos como diastema, rotaciones de piezas dentales o incluso la falsa imagen positiva de piezas dentales en realidad ausentes 25,26 .…”

“…No obstante, algunos recientes trabajos alertan sobre el uso de estas marcas de mordedura con fines de identificación basada en características específicas de la dentición 25,26 . Así, en experimentos sobre mordeduras humanas se ha podido identificar la presencia de falsos positivos a hallazgos como diastema, rotaciones de piezas dentales o incluso la falsa imagen positiva de piezas dentales en realidad ausentes 25,26 . Las características del complejo comportamiento elástico de la piel, de respuesta impredecible a los efectos de presión, han llevado a sugerir el uso con extremada precaución con fines de identificación de las marcas de mordedura 27,28 .…”