New forensic method uses electricity to lift prints from fired bullets

Researchers at Maynooth University in Ireland have developed a novel electrochemical method to reveal fingerprints on fired bullet casings, a task previously considered nearly impossible due to the extreme heat and pressure inside gun barrels that destroy traditional fingerprint residues. Unlike conventional techniques that rely on sweat and skin oils to visualize prints, this new approach uses the fingerprint residues as a protective stencil on the brass surface. When a low voltage is applied, a metallic coating forms only in the spaces between fingerprint ridges, producing a high-contrast negative image even if the residues have been thermally altered during firing. While promising, the technique is still in early development and faces challenges related to different metal types, surface corrosion, and environmental exposure. The researchers have demonstrated good results on brass but note that materials like stainless steel or aluminum, as well as extreme heat or long-term exposure, may reduce effectiveness. Before the method can be adopted in forensic practice and withstand legal scrutiny, it requires extensive validation, blind testing, and inter-laboratory