Ole Miss researchers make 3D 'ghost guns' traceable. Here's how it works.

No serial numbers or background checks required; are 3D-printed guns the perfect murder weapon? Maybe not after a University of Mississippi chemistry professor and a graduate student developed a method to identify chemical fingerprints these guns can leave behind.

Sometimes referred to as "ghost guns," 3D-printed guns are made using printers that create objects using polymers. Computer files containing the plans for making guns drive the printer. 

The first functional 3D-printed gun was designed in 2013 and plans were downloaded more than 100,000 times in the first two days they were made available.

That drove associate professor James Cizdziel and graduate student Oscar "Beau" Black to develop a method for law enforcement to track the origin of a plastic gun if it was used in a crime.

3D-printed guns 'do exactly what they were designed to do'

The two began creating functional 3D-printed firearms, either .22-caliber or .38-caliber handguns, which used certain metal parts to comply with a federal ban on weapons that aren't picked up by metal detectors. They test-fired them 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 test firings provided samples, and the two used the analytical technique mass spectrometry to identify and characterize the various polymer types in 3D-printed gun evidence.

"We can positively identify the type of polymer used in the construction of the gun from flecks or smears of plastic on bullets, cartridge cases and in gunshot residue collected on clothing," Cizdziel said. 

Tracing evidence to suspects

The evidence left behind by different polymers used in printing guns was put into a database for forensics experts to use for comparison if a 3D-printed gun was used in a crime. Cizdziel explained that if a 3D-printed gun was used in a crime, investigators can determine what polymer was used and then determine if there is a link between the polymer and a suspect.

"Our growing database provides a second means of identification or grouping of samples, alleviating the need for subjective interpretation of the mass spectral peaks," Cizdziel said. "We also published fingerprinting protocols on surfaces of 3D-printed guns. 

"Overall, we demonstrated that our methods are particularly useful for investigating crimes involving 3D-printed guns."

Their work also resulted in a book, "Forensic Analysis of Gunshot Residue, 3D-Printed Firearms, and Gunshot Injuries: Current Research and Future Perspectives."

Black recently graduated, but his 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."

Mississippian Brian Broom is an avid outdoorsman who has worked for the Clarion Ledger for nearly 30 years. To read more of his stories, please subscribe today.Contact Brian Broom at 601-961-7225 or bbroom@gannett.com. Follow Clarion Ledger Outdoors on Facebook and @BrianBroom on Twitter.