Bite Mark

The National Institute of Standards and Technology (NIST) has reviewed the scientific foundations of bitemark analysis, a forensic technique in which marks on the skin of a biting victim are compared with the teeth of a suspected biter. NIST has published its findings in a draft report, Bitemark Analysis: A NIST Scientific Foundation Review, which will be open for public comment for 60 days. 

The draft review finds that “forensic bitemark analysis lacks a sufficient scientific foundation because the three key premises of the field are not supported by the data. First, human anterior dental patterns have not been shown to be unique at the individual level. Second, those patterns are not accurately transferred to human skin consistently. Third, it has not been shown that defining characteristics of those patterns can be accurately analyzed to exclude or not exclude individuals as the source of a bitemark.” 

Organization of Scientific Area Committees for Forensic Evidence (OSAC) is developing documentary standards for each forensic discipline. Standards under consideration as well as approved standards are available in the OSAC Registry.

The bibliographies (here and here) contain citations to published articles on bite mark analysis. If you need access to these articles, contact Sarah Rackley Olson.

Article by the Innocence Project identifying concerns with bite mark analysis and discussing five cases where individuals were convicted based largely on bite mark analysis, only to be proven innocent through DNA years later.

As of 2016, the ABFO Standards and Guidelines no longer permit conclusions of “exact match” or that a perpetrator made a mark without a doubt. This marks a significant change in the field. The strongest conclusion permissible now is that a person is “not excluded as having made the bitemark.” See p. 94 and 102.

See pp. 106-118 for bite mark methodology guidelines, including methods to preserve bite mark evidence (p. 107), bite mark analysis guidelines (p. 112), bite mark terminology guidelines (p. 114), and guidelines for investigative and final bite mark reports (p. 117). The American Board of Forensic Odontology has an expert locator service available here.

Their 2018 Standards are available here. See p. 3-4 for the limitations on permissible conclusions.

The 2016 President’s Council of Advisors on Science and Technology Report concluded that “bitemark analysis does not meet scientific standards for foundational validity, and is far from meeting such standards. To the contrary, available scientific evidence strongly suggests that examiners cannot consistently agree on whether an injury is a human bitemark and cannot identify the source of bitemark with reasonable accuracy.” (p. 87)

4-part Washington Post series on the flawed “science” of bite mark analysis

See pp. 173-176 for the National Research Council’s evaluation of forensic odontology. The report finds “there is continuing dispute over the value and scientific validity of comparing and identifying bite marks.” p. 173. The report lists the following concerns:

• “Bite marks on the skin will change over time”;
• Bite marks “can be distorted by the elasticity of the skin, the unevenness of the surface bite, and swelling and healing”;
• “Distortions in photographs and changes over time in the dentition of suspects, may limit the accuracy of the results”;
• “Different experts provide widely differing results and a high percentage of false positive matches of bite marks using controlled comparison studies”;
• and concerns about a lack of supporting research, a lack of a central repository of bite marks and patterns, and the potential for examiner bias.

FBI report on bite mark photographic distortion and corrective measures, using a description of methods used in the analysis of bite mark evidence from a 1973 homicide case that was prosecuted in 2000.

A law review article on State v. Temple, 302 N.C. 1 (1981) where the NC Supreme Court held that testimony regarding bite marks identification analysis is admissible as long as the trial court can verify the scientific methods used were accurate and reliable. Includes a summary of the case, background, and an analysis of the opinion.

Document outlining NIST's approach to conducted scientific foundation reviews (including data sources used, evaluation criteria, and expected outputs) of DNA mixture interpretation, bitemark analysis, digital evidence, and firearms examination.

Nov. 2016 Journal of Law and Biosciences article.

Blog created by David C. Averill, DDS, and past president of the American Board of Forensic Odontology. It includes articles and news reports on the controversial area of bite mark analysis, as well as information about cases where bite mark evidence has played a role.

Bite mark case where conviction was reversed based on changes in the science being newly discovered evidence.

2020 Order granting a motion for a new trial based upon advancements in scientific understanding and American Board of Forensic Odontology (ABFO) guidelines that would compel a different expert opinion if the case were tried today. In 2016, the ABFO Standards and Guidelines were changed significantly to no longer allow a conclusion of “exact match” or that a perpetrator made a mark without a doubt. The strongest conclusion permissible now is that a person is “not excluded as having made the bitemark.” 

Article by the Innocence Project identifying concerns with bite mark analysis and discussing five cases where individuals were convicted based largely on bite mark analysis, only to be proven innocent through DNA years later.

715 S.E.2d 635, N.C.App., September 20, 2011 (NO. COA10-1344)

Defendant argued that the forensic odontologist improperly invaded the province of the jury by testifying that the defendant caused the bite mark on the child. The court held that even if the specific assertions that the defendant was the one who made the bite marks were not allowed, the jury still would have heard other evidence with respect to the mark that was not objected to. Therefore, the jury had enough evidence to come to its own conclusion regardless of the assertions of the expert.

A law review article on State v. Temple, 302 N.C. 1 (1981) where the NC Supreme Court held that testimony regarding bite marks identification analysis is admissible as long as the trial court can verify the scientific methods used were accurate and reliable. Includes a summary of the case, background, and an analysis of the opinion.

For a copy of the Innocence Project’s amicus brief in a Frye challenge to the admissibility of bite mark evidence, email Sarah Rackley Olson.