NIST Seeks Public Comments on Draft Report of Forensic Bitemark Analysis

Illustration of a typical human dentition viewed in standard anatomical position. Credit: K. Sauerwein/NIST

The National Institute of Standards and Technology (NIST) has published Bitemark Analysis: A NIST Scientific Review. The draft report will be open for public comments through Dec. 12, 2022.

The report details the findings from a NIST review of the scientific foundations of bitemark analysis, a forensic technique used to compare the marks on the skin of a biting victim with the teeth of a potential biter.

There were several key takeaways identified as part of the scientific review, including one that states that bitemark analysis is not supported by sufficient data:

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.

The Center for Statistics and Applications in Forensic Evidence (CSAFE) hosted a NIST-funded meeting in 2019 where forensic dentists, researchers, statisticians, lawyers and other experts addressed scientific questions around bitemark analysis. A meeting summary was written by Alicia Carriquiry, CSAFE director, and Hal Stern, CSAFE co-director. The CSAFE Bitemark Thinkshop Report provided information for the NIST review and has been published as a supplement.

NIST hosted a three-hour webinar on Oct. 27 to discuss the draft report and its findings. A recording of the webinar will be posted soon on the NIST website. For more information, visit https://www.nist.gov/news-events/events/2022/10/webinar-bitemark-analysis-nist-scientific-foundation-review.

Read the NIST news release on the report at https://www.nist.gov/spo/forensic-science-program/bitemark-analysis-nist-scientific-foundation-review.

Insights: Surveying Practicing Firearms Examiners

INSIGHTS

Surveying Practicing Firearms Examiners

OVERVIEW

In recent years, there has been much discussion and debate regarding firearm examiner testimony, but little is known empirically about the actual practices of firearm examiners in conducting casework. Researchers funded by CSAFE conducted a survey of practicing firearms examiners to better understand the conditions of their casework, as well as their views of the field and its relations with other parts of the justice system.

Lead Researchers

Nicholas Scurich
Brandon L. Garrett
Robert M. Thompson

Journal

Forensic Science International: Synergy

Publication Date

2022

Publication Number

IN 127 IMPL

Goals

1

Gain insights into the day-to-day casework and lab procedures of firearms examiners

2

Find what examiners believe impacts the quality of their work

3

Learn the examiners’ opinions of statistical models, new technology, and misunderstandings from judges and jurors in regard to their profession

The Study

Scurich et al. posted a survey on the Association of Firearms and Toolmark Examiners (AFTE) member forum from July to November of 2020. Participation was voluntary, anonymous, and uncompensated. A total of 79 AFTE members provided usable responses.

The survey asked about several topics, including:

Results

Frequency

What percentage of your cases result in an identification conlusion?

Frequency

What percentage of your cases result in an exclusion/elimination conlusion?

The percentage of identification results vs. elimination results

From the 79 responses, Scurich et al. learned the following:

Focus on the future

 

Further work should explore the impacts of lab policies and evidence submission practices on examiners.

New training and educational opportunities—for both firearm examiners and the consumers of firearm examiner testimony—could provide benefits and promote clearer understanding of the strengths and limitations of firearm examination.