Two seizures of counterfeit 100 US$ bills related to the same indicative number were submitted for processing of latent fingerprints. On one group of notes, identifiable fingerprints could be detected by the routine application of amino acid reagents. In the second case, this technique gave no results, even on deliberately deposited prints. Fingerprints could be revealed, however, by cyanoacrylate fuming followed by magnetic powder. Comprehensive paper analysis showed that banknotes from both seizures differed remarkably by chemical composition as well as paper macroscopic properties. The difference in surface free energy (related to surface tension) of the banknotes in the two groups seemed to be the major factor responsible for the great variance in fingerprint detectability.