UK researchers develop new technique for collecting latent fingerprints from metal surfaces
Researchers have developed a new technique for producing high-resolution biometric fingerprint images from the most challenging metal surfaces, including knives and firearms, Phys.org reports.
A team of experts from the University of Nottingham and the University of Derby have used Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) to produce fingerprints from surfaces conventional imaging fails with. They were able to take fingerprints with enough detail to see the position and shape of sweat pores, and to gather prints from samples stored under ambient conditions for up to 26 days.
“This raises the possibility of being able to reliably visualize fingerprints on surfaces previously thought to be devoid of such crucial evidence,” says research leader Dr. James Sharp of the University of Nottingham’s School of Physics and Astronomy. “ToF-SIMS imaging has the potential and could be a valuable tool in helping to visualize fingermarks on objects such as stainless-steel knife blades and firearms.”
University of Derby Undergraduate Program Coordinator for Forensic Science Adam Long says metallic surfaces tend to be very difficult to retrieve fingerprints from, due to common physical and environmental conditions at crime scenes, the age of the print, and how developing reagents react with metals.
“A common example of the difficulties investigators face, comes from examining fired bullet casings,” Long explains. “The high temperatures, pressure and friction caused when a bullet is fired makes fingerprints extremely fragile and this, combined with other factors, often results in their apparent removal or obliteration. This technique is non-destructive and can be used repeatedly to image fingerprint marks without compromising their quality.”
The UK’s Ministry of Defense also developed a chemical for recovering latent fingerprints from challenging surfaces such as used ammunition casings in 2017.
Brass, aluminium, and stainless steel surfaces were tested by the researchers. While traditional fingerprinting techniques showed degraded data after 8 days, measuring the mass of different molecules with an ion beam enabled the researchers to detect and visualize fingerprint secretions with the ToF-SIMS technique 26 days later on samples from all six donors.
Further testing is needed to demonstrate the applicability of the technique to a broader range of fingerprints and surfaces.