Fingerprint Analysis Reveals What You Touched

Using a technique called desorption electrospray ionization (Desi), a fingerprint analysis can reveal not just the identity of a person, but also what he or she has touched. R. Graham Cooks and his team from Purdue University spray an electrically charged liquid on some part of a fingerprint, which allows the transfer of electrical charge to the fingeprint molecules. This fingerprint is then analyzed using mass specrtoscopy and the process is repeated in order to create a two-dimensional image. Particles of cocaine, RDX or other poisons left on glass, paper or plastic can be analyzed using this technique.

For further reference read the article that appeared in The New York Times