Bitemark Case Study 2

History: A victim was attacked in the parking lot of a shopping center during a robbery and car heist attempt. The victim, who died of multiple stab wounds, was bitten by the perpetrator during the altercation. The bitemark was used as part of the evidence in the case which ended in a conviction (Figures 6-7).

Figure 6.
Adobe Photoshop® was used to digitally scan and outline the biting edges of the models of a suspect dentition which were transferred to the overlay. The overlay was then compared to the bitemark image.
Figure 7.
A comparison showing a suspect dentition overlaid on a bitemark at the start of the biting (A) and at the end of the biting (B). Other evidence in this case included DNA evidence, a confession, surveillance video and witnesses.

There are many physical and physiological factors that must be considered when examining bitemark evidence. These include, but are not limited to, biting dynamics, skin tension lines, all three planes of the suspect dentition (mesial-distal width, buccal – lingual width and incisal height), arch shape, missing or broken teeth and tooth rotations. It is beyond the scope of this course to attempt to teach the intricacies of bitemark case work, however it is possible to conceptually understand the overall process.

When the primary investigator has completed the analysis and, when appropriate, the comparison in a given case, there are several more steps involved before preparing the final case report. These include seeking a blinded second opinion by another independent investigator such that the second investigator only has information directly related to the injury pattern. “Blinding” is done to avoid the introduction of investigator bias. Assuming the second investigator reaches the same conclusion as the primary investigator after both have completed their blind analyses, the case report will then be prepared. The ABFO has report writing guidelines that should be followed and which flow logically from the start of the case to the preparation of the final report. The final report,6 when submitted to the respective agency or attorney, becomes part of the chain of evidence in the overall case and may be used in a future legal proceeding.

ABFO Guidelines for Investigative and Final Bitemark Reports6

The following ABFO Bitemark Report Writing Guidelines propose a format for written bitemark case reports. These guidelines are suggestions for the form and content of the report. Diplomates may be asked to provide preliminary or investigative reports. Those preliminary reports may follow the same general guidelines without being conclusive in nature. Reports may be structured into the following sections:

Introduction: This section provides the background information, the “who, what, when, where and why” data related to the case.

Inventory of Evidence Received: This section lists all evidence received by the Forensic Odontologist and details the source of the evidence.

Inventory of Evidence Collected: This section lists the nature, source, and authority for evidence collected by the Forensic Odontologist.

Opinion Regarding the Nature of the Patterned Injury or Injuries: This section states the author’s opinion as to whether the patterned injuries in question are bitemarks, using ABFO terminology. Only one comparative term is used for each opinion in this part of the report.

Methods of Analysis: This section describes the analytic methods used for the patterned injuries determined to be bitemarks.

Results of Analyses: This section describes the results of the comparisons and analyses.

Opinion: This section states the author’s opinion of the relationship between one or more bitemarks and a suspected biter or biters using ABFO Bitemark Terminology. Only one comparative term is used for each opinion in this part of the report.

Disclaimer: Disclaimer statements may be included to convey that the opinion or opinions are based upon the evidence reviewed through the date of the report. The author may reserve the right to file amended reports should additional information become available.