NIST Supports Accurate Forensic Science Measurements with Updated Standard Reference Materials

CSAFE Standard Bullet

What role do measurements play in analyzing evidence? It’s actually pretty significant, but accuracy is key. When forensic laboratories use tools such as instruments, microscopes or DNA profiling kits it’s important to have physical standards.

The National Institute of Standards and Technology develops standard reference materials (SRMS) to help labs calibrate their analytical instruments. In September 2018, NIST released updated versions of two SRMS.

The Standard Bullet

Every bullet fired from a gun leaves unique markings. If a bullet is recovered at a crime scene, investigators can test-fire a suspect’s weapon to compare these bullet signatures.

A standard bullet is not real, but it looks like a typical bullet you’d see fired from a gun. Each standard bullet contains those markings called striations, simulating the impressions left by a gun.

Firearms examiners are able to use the standard bullet with advanced microscope technology to measure the striations on the NIST standard bullet. This helps test the instrument’s calibration and analysts can compare results to NIST data. A new manufacturing method has led to a more cost effective standard bullet, allowing access to more laboratories.

In a news release, the NIST the physical scientist who led the project stated, “This is one way to catch problems quickly. That way you can diagnose and fix the problem before doing additional casework.”

CSAFE not only owns a standard bullet, but our team’s firearm and ballistic research is leading to new technologies for bullet matching and cartridge case comparison. Find CSAFE tools for analyzing bullet lands or comparing cartridge case images on our resource page. CSAFE Director Dr. Alicia Carriquiry also recently contributed to an article highlighting the need for consistent standards in the firearms examination field.

Human DNA Quantitation

NIST also released a new SRM for Human DNA analysis. While the CSAFE team does not research human DNA, we partner with organizations such as the Innocence Project who work with this type of evidence.

If investigators discover blood or other biological evidence at a crime scene, analysts can extract DNA to create a profile to compare suspects. Accuracy relies on an analyst knowing how much DNA is in the extract prior to processing. NIST’s new standard for creating suspect DNA profiles assists with calibration for this type of measurement.

Learn more about other types of SRMs manufactured by NIST to ensure reliability of scientific evidence. Find additional information on NIST work and its partnership with CSAFE in our January 2018 blog post.


Forensics, Justice, and the Case for Science-Based Decision Making

*The information below is an excerpt from CSAFE researcher and University of California, Irvine’s Professor of Criminology, Law and Society Dr. Simon Cole’s recent blog post “Forensics, Justice, and the Case for Science-Based Decision Making” originally published November 14, 2018 on the Union of Concerned Scientists website. Review the full blog post.

Forensic science—and the language forensic scientists use to talk about their findings–has real-world impacts, sometimes life-or-death impacts, for real people. If the criminal justice system is going to really serve the cause of justice, it needs to be informed by the best available science.

In recent years, some progress has been made toward recognizing the inherently probabilistic nature of all scientific evidence and seeking ways of communicating those probabilities to lay audiences. The ULTRs signal that the DOJ is not yet ready to join that effort. This is unfortunate, given the DOJ’s power and influence.

Scientists don’t need to know anything about forensic science to understand that categorical statements of certainty are not plausible. Any scientist can help by letting the DOJ know that their statements are not scientifically credible and that the opinions of individual scientists and scientific institutions should be taken seriously by the nation’s most important purveyor of justice.

Overstating the certainty of forensic evidence has been implicated in many miscarriages of justice. And it is scientifically wrong. The people who are the ultimate consumers of forensic evidence deserve better.