Researchers at Maynooth University developed an electrochemical technique that converts brass casings into electrodes to deposit material into microscopic grooves and reveal latent fingerprints. The method, reported in Forensic Chemistry by Colm McKeever and Eithne Dempsey, produced usable prints on brass samples up to 16 months old. A compact potentiostat could enable portable field kits, but the approach remains a proof of principle and requires further validation across materials and conditions.
New Electrochemical Method Reveals Fingerprints on Spent Bullet Casings — Even Months Old
Researchers at Maynooth University developed an electrochemical technique that converts brass casings into electrodes to deposit material into microscopic grooves and reveal latent fingerprints. The method, reported in Forensic Chemistry by Colm McKeever and Eithne Dempsey, produced usable prints on brass samples up to 16 months old. A compact potentiostat could enable portable field kits, but the approach remains a proof of principle and requires further validation across materials and conditions.
09:55 PM, 11/10/2025Science
Scientists Recover Fingerprints from Fired Bullet Casings Using Electrochemistry
What happened: Researchers at Maynooth University in Ireland have demonstrated an electrochemical technique that can reveal latent fingerprints on spent brass bullet casings—surfaces long thought impossible to fingerprint after firing.
How the method works
The team, led by Colm McKeever and Eithne Dempsey and publishing in Forensic Chemistry, uses a low-voltage electrochemical process to turn the brass casing into an electrode. By applying a controlled potential, chemicals are driven to the casing’s surface and deposited into microscopic grooves left by fingerprint ridges. The burnt residue remaining on the casing acts like a stencil, guiding deposition so fingerprint detail becomes visible almost immediately.
“Using the burnt material that remains on the surface of the casing as a stencil, we can deposit specific materials in between the gaps, allowing for the visualization,” McKeever said in a press statement.
Key results
The researchers focused on brass (the most common casing material) and were able to recover usable prints from samples aged up to 16 months. A central device in the technique is a potentiostat, which controls the voltage; the authors note it can be miniaturized to roughly mobile-phone size, raising the possibility of compact field kits.
Limitations and next steps
The study is an early proof of principle. The authors emphasize the need for further work to:
- Validate the technique’s accuracy and reliability across a wider range of conditions, casing types (e.g., aluminum alloys, steel) and ages.
- Standardize procedures to avoid contamination or false positives in operational settings.
- Adapt the method to other difficult-to-fingerprint metallic surfaces such as knives, coins and different firearm components.
Today, spent casings typically help match a projectile or firing weapon; if refined and validated, this electrochemical approach could extend that capability to link a casing to the individual who handled or loaded the ammunition.
Why it matters
This research revisits a long-standing forensic assumption and demonstrates how targeted surface chemistry and compact instrumentation may unlock new evidence from old evidence. While promising, the method must pass rigorous validation and operational testing before adoption in forensic laboratories and crime-scene workflows.