In 2013, blueprints for the “Liberator”—the world’s first 3D-printed gun—appeared online and were downloaded 100,000 times in just two days. The U.S. State Department requested the company remove the blueprints after a couple days but, like everything else on the internet, the blueprints persist on other sites and through already-downloaded files.
While 3D-printed guns have already been found at crime scenes, an increase is expected in coming years as 3D printing technology advances and costs decrease. That’s one thing that pushed James Cizdziel, professor of chemistry and biochemistry at the University of Mississippi, to take a proactive approach to the problem.
“There is concern with these 3D -rinted guns because they have no serial numbers,” Cizdziel told the audience during the Innovations in Technology to Advance Forensic Science oral session at Pittcon 2020 last week. “They have few metal components, making them easy to bring into high-security areas, they are easily disposed of, and they are relatively cheap and easy to make, especially for people with no traditional access to firearms.”
While reviewing the literature, Cizdziel realized there was no published knowledge on 3D-printed guns and the threats they pose. So, he worked with colleague Oscar Black and chemists at JEOL to answer two specific questions: To what extent does ballistic trace evidence differ from 3D-printed guns to traditional firearms?; and Do existing analysis methods apply to 3D-printed (3DP) guns?
For their study, published in Forensic Chemistry, the researchers 3D-printed a fully functional .022 caliber firearm generated from the “Washbear” blueprint files obtained online. They constructed barrels from different polymers, seeking to determine whether DART-MS could be used to readily detect and identify traces of polymer and organic GSR compounds on the bullets, cartridge cases, and in GSR collected from clothing.
While detecting polymer in the trace evidence was challenging, some of the stubs had particles that looked like plastic under a microscope. Upon further analysis, DART-MS obtained clear spectra that matched the plastic from the gun. Polymer was not detected in the GSR stub solvent washes—rather, those spectra were dominated by the compounds typical of organic GSR.
According to the study, DART-MS readily detected three chemicals commonly found in firearm propellants (ethyl centralite, methyl centralite and diphenylamine) on the bullet and cartridge case, as well as in the solvent wash of the GSR stub. Both scraping of the material firearm evidence and solvent washes of the GSR stubs were effective in detecting ethyl centralite. As a control, an SEM stub that was not exposed to GSR was extracted following the same procedure for the stubs used to sample GSR. After analysis, the blank stub showed trace phthalates and an unknown spectrum peak that was not observed in the GSR-exposed stub.
Based on study results, Cizdziel has already created a searchable database of DART mass spectra for about 100 common 3DP polymers—a database he is looking to expand both on his own and with the help of NIST. Cizdziel hopes that, eventually, the database will be available for approved groups to add their research and findings.
Overall, Cizdziel said it’s important for forensic scientists and crime science investigators to recognize that the traditional traceology approach must be adapted when investigating a scene where a 3DP firearm is suspected.
3DP toolmarks, for example, pose a different set of circumstances and problems. “Unlike traditional bullets, there were no reproducible barrel striations so there are no toolmarks,” Cizdziel said. “But, unique firing pins leave impressions that are feasible evidence, as well as unique flecks of polymer or plastic on the retrieved bullet.”
For latent fingerprints, there was initial concern that the layering effect 3DP uses may cause difficulties in development and visualization, but Cizdziel’s team tested a number of methods successfully, although black magnetic powder without fuming worked best.
Cizdziel said he will continue to expand the 3DP polymer database while pushing forward on trace evidence, including metabolized drugs and DNA left in latent prints on 3DP firearms.
Photo: The Liberator- a 3D-printable single shot handgun, the first such printable firearm design made widely available online.