Criminals sweat it

Criminals are one print less secure in their crime thanks to developments in forensic science that allow fingerprints to be lifted from paper very easily. Researchers in Israel have developed a way to obtain a negative fingerprint from paper that does not depend on the chemical composition of the residue left behind. In countless criminal and fraud cases knowing who handled specific documents or folding money can be the crucial evidence on which a conviction hinges. Daniel Mandler and Joseph Almog at the Hebrew University of Jerusalem have used gold nanoparticles to first develop a latent print where the nanoparticles stick to the paper rather than the print residue, thus producing a negative of the print, which is then developed further with silver to blacken the paper and expose the fingerprint.