Maynooth University unveils a potential breakthrough in firearm forensics
Researchers at Maynooth University have announced a method that could transform how investigators handle gun-related crimes by showing fingerprints on brass bullet casings. The team, led by Dr. Eithne Dempsey and PhD student Colm McKeever from the Department of Chemistry, says their electrochemical approach can visualise fingerprint ridges on surfaces once thought to be fingerprint‑proof. If validated, this technique could become a valuable tool for linking individuals to ammunition used in a crime scene, even after the weapon was fired.
How the method works
The core idea is to turn the ammunition casing into an active surface in an electrochemical cell. Brass casings, long resistant to conventional fingerprint detection, are coated with a thin layer of specialised polymers that help reveal hidden print ridges. A modest voltage is applied via a device called a potentiostat, which controls the electrical potential in the solution surrounding the casing. Under these controlled conditions, the solution’s chemicals are drawn to the spaces between fingerprint ridges, creating a high‑contrast image of the print.
Unlike other forensic techniques that rely on harsh chemicals or high-energy equipment, this process uses non-toxic polymers and relatively low energy. The result is a visually distinct print on a surface that would otherwise appear blank after the heat and gases of firing have erased conventional traces.
The science in plain terms
In simple terms, the casing acts as an electrode in an electrochemical cell. When voltage is applied, chemical reagents migrate to the surface and preferentially line the tiny gaps where a fingerprint’s ridges rest. That spatial selective deposition makes the otherwise invisible ridge pattern visible under appropriate imaging, enabling analysts to read a print even on brass—a material historically challenging for standard fingerprint methods.
Lead researcher Dr. Eithne Dempsey notes that the technique aims to preserve the integrity of potential evidence while avoiding hazardous chemicals. “The Holy Grail in forensic investigation has always been retrieving prints from fired ammunition casings,” she says. “Traditionally, the intense heat of firing destroys biological residue. However, our technique has been able to reveal fingerprint ridges that would otherwise remain imperceptible.”
Validation, limitations, and next steps
The Maynooth team emphasizes that their method is at the validation stage. While the initial results are promising, the researchers acknowledge that rigorous testing is essential before any police or forensic laboratory adoption. The technique will need to demonstrate reliability across different calibers, ammunition brands, and environmental conditions such as moisture, dirt, and abrasion from handling. Standardisation, reproducibility, and the assessment of potential contamination risks are all critical hurdles to clear.
According to the team, the approach could be configured into a compact, field‑ready kit built around a portable potentiostat. If such a device proves robust in field settings, investigators might be able to quickly secure usable prints at crime scenes, speeding up leads and potentially narrowing down suspects.
Broad forensic implications and future directions
The research, funded by Research Ireland and Maynooth University, has been published in the forensic science journal Forensics Chemistry. Beyond firearms crime, the researchers suggest the principle could extend to other metallic surfaces where prints are difficult to detect, including in arson investigations or cases involving metal artefacts. Dr Colm McKeever explains that turning the ammunition casing into an active electrode opens up a wider range of surface chemistry manipulations, enabling tailored approaches for different materials.
While the promise is clear, a measured view is warranted. The team is pursuing collaborations with forensic laboratories to carry out independent validation studies. If successful, this method could complement existing fingerprint techniques rather than replace them, offering an additional line of evidence that helps investigators connect individuals to the weapons and ammunition involved in crimes.
Why this matters for law enforcement
Fingerprints From Fired Casings could, in time, provide a crucial link between a crime scene and a person who handled ammunition before a shooting. In practice, this would augment investigative leads, aid in reconstructing events, and potentially accelerate case resolution. The Maynooth work represents a notable example of how cutting‑edge chemistry and electrochemistry can intersect with real‑world policing challenges, bringing science closer to the street without sacrificing safety or practicality.
