| The unambiguous identification of a counterfeiter by fingerprint evidence hinges on the determination whether the fingerprint was placed on the counterfeit note before (FB) or after inking (FA). Three counterfeiting methods, including color copying, offset printing and inkjet printing have been investigated.; A number of techniques, including 5-methoxyninhydrin/ZnCl{dollar}sb2{dollar}, DFO, DMAC, physical developer, colloidal gold, membrane transfer, vapor development, and finally, Eu-DTPA/OP have been explored in an attempt to distinguish between fingerprints on counterfeit currency before and after the inking. Most methods fail to show difference between FB and FA fingerprints because of the permeability problem of the inks. However, the lipid-sensitive Eu-DTPA/OP procedure partially overcomes the permeability problem and shows substantial difference between FB and FA fingerprints for color copying. There are subtle differences between before and after fingerprint fluorescence spectra (both 5-methoxyninhydrin/ZnCl{dollar}sb2{dollar} and Eu-DTPA/OP). Given that one has to contend with finger contamination, the spectroscopy at present may not be practically useful, but it shows potential if proper rare-earth-based strategies are used. |
