Registry of Approved Standards Adds Two New 3D Firearm Analysis Standards
by Casey J. Bastian
In an effort to improve forensic firearm and toolmark analysis, the Organization of Scientific Area Committees for Forensic Science (“OSAC”) has updated its Registry of Approved Standards. OSAC is administered by the National Institute of Standards and Technology (“NIST”) and was launched in 2014. NIST claims that “these standards are technically sound and will help forensic laboratories improve their processes and methods.”
The two new standards are: “ANSI/ASB Standard 062, Standard for Topography Comparison Software for Toolmark Analysis” and “ANSI/ASB Standard 063, Implementation of 3D Technologies in Forensic Firearm and Toolmark Comparison Laboratories.” These represent the 100th and 101st standards added by OSAC to the Registry. “These standards give labs guidance on purchasing and setting up a 3D system, validating it to ensure that it produces accurate results, and implementing it into their workflow,” said Erica Lawton. She is the chair of OSAC’s Firearms and Toolmarks Subcommittee and is also a firearms examiner at the Alabama Department of Forensic Sciences. She helped to ensure that the new standards were approved.
“The 3D approach is not yet mainstream, but many labs are looking into it,” said Xiaoyu Alan Zheng who works with NIST as a forensic firearm and toolmarks researcher. As an OSAC member, Zheng also helped work on these new standards. For over 100 years, the traditional method for firearm and toolmark analysis involved a subjective manual process. Examiners trying to link a bullet or cartridge case to a specific gun would have to examine and make comparisons under a split screen microscope. Forensic experts would look for microscopic marks created as the projectile left the barrel, moving them under the microscope to see if the observed marks lined up.
The 3D method uses an algorithm to generate “a numerical score that describes how closely the two surfaces match.” This “match statistic” describes the uncertainty in the analysis, “and police investigators, jurors and others can use it when weighing the evidence.” The traditional method leaves only the expert’s subjective opinion, which research has shown can easily be subject to errors and biases. The 3D method is also more efficient. Evidence no longer has to change hands between examiners or departments. The digital file can be readily shared for validation purposes. Zheng added, “There are a lot of benefits in terms of both reliability and efficiency, and the discipline is moving in this direction.”
In the U.S., no regulatory authority sets mandatory standards or requirements that must be followed by laboratories. However, many labs voluntarily follow OSAC registry standards. NIST operates OSAC as part of its Forensic Science Program. NIST also assists labs in implementing OSAC Standards via a “cooperative agreement with the American Academy of Forensic Sciences.”
Lawton intends to adopt these standards in the Alabama lab where she works. “We are right at the cusp of this transition. Having these standards available now, rather than after labs have already installed new systems, will help ensure that people get this right the first time around,” said Lawton. Other standards related to fire and explosion investigations, toxicology, and sexual assault examinations are currently being drafted by OSAC.
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