Researchers at Maynooth University have developed a proof‑of‑concept technique that recovers highly detailed fingerprints from bullet casings heated in a furnace. Using a tailored chemical solution and a small electrical voltage, the method visualises residue on the metal to reveal ridge and pore detail. Tests showed prints could be recovered after more than a year of storage, but the approach has not yet been validated on casings actually fired from guns. Further work is needed because gaseous blowback and other firing effects may erase prints in real shootings.
Forensics Breakthrough: High‑Detail Fingerprints Recovered from Super‑Heated Bullet Casings
Researchers at Maynooth University have developed a proof‑of‑concept technique that recovers highly detailed fingerprints from bullet casings heated in a furnace. Using a tailored chemical solution and a small electrical voltage, the method visualises residue on the metal to reveal ridge and pore detail. Tests showed prints could be recovered after more than a year of storage, but the approach has not yet been validated on casings actually fired from guns. Further work is needed because gaseous blowback and other firing effects may erase prints in real shootings.
06:40, 08.11.2025Security
‘Holy Grail’ of Forensics: Fingerprints Recovered from Heated Bullet Casings
Researchers at Maynooth University in Ireland report a proof‑of‑concept method that can recover human fingerprints from bullet casings exposed to very high temperatures. The technique revealed exceptionally fine detail — including ridge structure and pores — that could be forensically meaningful.
What the team did: Chemist Eithne Dempsey and her former PhD student Colm McKeever developed a chemical treatment combined with a small applied voltage to visualise biological residue remaining on metal casings after intense heating. In their experiments, casings were heated in a furnace to simulate the extreme temperatures of firing.
"The Holy Grail in forensic investigation has always been retrieving prints from fired ammunition casings," said Dempsey. "Traditionally, the intense heat of firing destroys any biological residue. However, our technique has been able to reveal fingerprint ridges that would otherwise remain imperceptible."
McKeever explains that the residual burned material on the casing surface acts like a stencil. By turning the metal casing into an electrode, the team drove controlled chemical reactions that deposit contrasting material into the gaps, making ridge detail visible.
Notably, the researchers were able to recover fingerprints from casings that had been heated and then stored for more than a year, demonstrating the technique's potential for real‑world evidence preservation.
Limitations and next steps: The study is an early proof of concept and did not use casings actually fired from firearms. The authors caution further validation is required because gunfire can produce not only heat but also rapid gaseous blowback and other forces that may remove or alter prints. Additional testing on live‑fire casings and a wider range of ammunition types and firing conditions will be needed before the method can be adopted in casework.
The work was published in the journal Forensic Chemistry. While promising, the technique complements rather than yet replaces existing forensic approaches, and the search for a reliable, widely applicable method to recover prints from fired ammunition continues.
Implications: If validated on fired casings, the method could aid investigators by providing highly detailed biometric evidence (ridges and pores) that supports identification, helping to link suspects to weapons in criminal investigations.