Refined fingerprint technique could give criminals a nasty shock

The new method builds upon previous research of Dr John Bond OBE from the University of Leicester Department of Criminology, who in 2012 found a technique that reveals previously undiscovered fingerprints on metal, especially gun shell casings, by applying a large voltage to the metal and then adding ceramic beads coated with a fine powder to the surface.

This latest development refines the technique by applying the powder to a corroded spent shell casing that is electrostatically charged.

This method offers practitioners an alternative means of visualising fingerprint corrosion on brass and may be easier to use in practice than the current method, particularly in difficult situations such as when examining aged fingerprint deposits or fingerprints exposed to environmental extremes -- such as being immersed in a fluid, exposed to dust particles or manually wiped.

Dr Bond said: "Visually fingerprinting corrosion in brass is easily achievable and this latest development should be viewed as an additional means of identifying offenders in gun-related offences.

"This work has been carried out by myself and Dr Xu Jingyang from the ZPC and is a development of my invention to recover fingerprints from spent brass shell casings. Together, we have perfected an adaptation of my invention which has been shown to produce visible fingerprints in corrosion on the shell casing."

The electrostatic technique is superior for aged prints as a result of metallic corrosion taking place, which enables the electrostatic technique to work more effectively.

The team suggests the effectiveness of the electrostatic adsorption method in developing aged fingerprints and the potential to develop fingerprints subject to environmental extremes make it a promising application to be further explored in the future.

The new apparatus is able to visualise fingerprints on metallic surfaces ranging from freshly deposited to up to 10 days old and could be used in criminal investigations to identify offenders using firearms.

A portable electrostatic generator can also be set up using common forensic lab equipment, and is therefore an affordable and easily-developed option for practitioners.

The work was carried out in the Fingerprint Laboratory at the ZPC and arose after one of Dr Bond's visits to the ZPC in 2015 following the signing of a Memorandum of Understanding between the ZPC and the University of Leicester to share world-leading expertise in forensic science, traditional police work and more.

Dr Jingyang added: "This work was inspired by the previous method developed by Dr Bond, based on which we had the idea to develop a portable and affordable device. I really appreciate Dr Bond's great support on this work and hope that we can move forward to further improve this method in the future."

The team hopes to develop a prototype device by the end of the year and a paper based on the new technique has been accepted for publication in 2017.