The application relates to a method for determining the presence of a residue on or within a fingerprint using mass spectrometric techniques. The mass spectrometric technique may be selected from MALDI-TOF-MS and SALDI-TOF-MS . A particulate suspension which acts as a matrix in matrix assisted laser desorption, and aids visualisation of the fingerprint, is applied to the fingerprint . Examples of suitable matrices are hydrophobic silica, titania, carbon black, fullerene, carbon nanotubes etc. Optionally, the fingerprint can be lifted using lifting tape.
