The forensic unknowns of 3D-printed guns

New Roman"”>The pair began creating functional 3D-printed firearms – either .22-caliber or .38-caliber handguns – that used certain metal parts to comply with a federal ban on weapons that aren’t picked up by metal detectors. They test-fired them under controlled and safe conditions at the Mississippi Crime Laboratory in Pearl and the Alabama Department of Forensic Sciences in Hoover, Alabama.

“When you discharge them, they do exactly what they are designed to do,” Black said. “You can shoot them multiple times. There was one we shot dozens of times with no visible wear and tear on it.”

The discharges generated samples to analyze. The duo also evaluated the differences in evidence between 3D-printed guns and conventional guns, and used the analytical technique mass spectrometry to identify and characterize the various polymer types in 3D-printed gun evidence.

This work was the beginning of creating a reference library of various polymer samples to provide the basis of categorizing an unknown sample. The reference library holds about 50 polymer samples.

Cizdziel and Black were assisted in their research by undergraduate students and Murrell Godfrey, director of the UM forensic chemistry program and associate professor of chemistry and biochemistry.

Black graduated Saturday (May 11), but the pair’s research is ongoing, including expanding and improving the 3D-print polymer reference library.

“The ultimate goal would have the reference library in a format that’s similar to the other reference libraries that are out there for fingerprints, etc.,” Black said. “Every different arena has a reference library that goes along with that discipline.”

Beyond work on the reference library, the twosome is examining DNA methods on 3D-printed firearms and studying the longevity of polymer evidence under weathering conditions. Cizdziel and Black also are working on a paper that presents all their scientific discoveries when it comes to 3D-printed firearms.

Not knowing what they might find in their investigations has led to some exciting findings and groundbreaking work, Cizdziel said.

“That’s when things get interesting,” he said. “When you don’t quite know what to expect.”

— Read more in Oscar Black et al., “Identification of polymers and organic gunshot residue in evidence from 3D-printed firearms using DART-mass spectrometry: A feasibility study,” Forensic Chemistry (27 May 2017) (DOI: 10.1016/j.forc.2017.05.003)