Finger post

11 November 2008

UK scientists have discovered a fingerprint 'developer' that can highlight invisible prints on almost any surface and read the text of a letter just from the envelope it was sent in.

Paul Kelly and colleagues at Loughborough University found that a disulphur dinitride (S₂N₂) polymer turned exposed fingerprints brown, as the polymer reaction was initiated from the near-undetectable remaining residues.

Traces of inkjet printer ink can also initiate the polymer. The detection limit is so low that details of a printed letter previously in an envelope could be read off the inside of the envelope after being exposed to S₂N₂.

'A one-covers-all versatile system such as this has obvious potential,' said Kelly.

'This work has demonstrated that it is possible to obtain fingerprints from surfaces that hitherto have been considered extremely difficult, if not impossible, to obtain,' said Colin Lewis, scientific adviser at the UK Ministry of Defence.

'The method proposed has shown that this system could well provide capabilities that could significantly enhance the tools available to forensic scientists in the future.'