A team of British scientists has developed a technique for recovering fingerprints from plastic banknotes, such as those to be introduced by the Bank of England in September.
The fingerprint recovery method by Loughborough University scientists uses the so-called vacuum metal deposition technique to create a thin layer of copper on the polymer surface of the banknote. Afterwards the fingerprints can be made visible using near-infrared illumination. Alternatively, the researchers found, a sheet of forensic gelatine can be used to lift the fingerprints from the note. By spraying the sheet with rubeanic acid, the fingerprints can be made visible even to the naked eye.
The researchers said the finding is extremely important as current techniques used to take fingerprints from paper banknotes won’t work on the polymer-based ones.
According to Paul Kelly, who led the research, the technique can be used to extract fingerprints from polymer-based notes used in fraudulent activities, to examine forged items, or to link suspects to stashes of stolen cash.
“The use of the near-infrared illumination procedure is of particular benefit because, allied to the copper deposition, it not only allows visualisation of print, it results in significant ridge detail,” Kelly said. “The thicker the copper deposition layer, the better the contrast, even on a substrate with a patterned background – and the new polymer notes are decorated with deliberately complex features.”
The major advantage of the technique is that the notes can potentially be released back into circulation. That’s possible because the gelatine lifting procedure provides a physical record of the development process.
The researchers want to further study the technique to see whether it could be used to read fingerprints from other polymer-based products, for example carrier bags.
The Bank of England, which plans to release the £5 polymer note this September, followed by a polymer £10 note in 2017 and a £20 note by 2020, has supported the research. Forensic science equipment suppliers Foster + Freeman and the Home Office Centre for Applied Science and Technology also participated in the project.