Fingermark visualisation on Euro banknotes – Current practices in European laboratories and outcomes of the 2024 collaborative exercise of the ENFSI Fingerprint Working Group

The 2024 fingermark visualisation collaborative exercise (visCE), organised by the ENFSI Fingerprint Working Group (FIN-WG), aimed to provide an overview of current practices among European laboratories in the detection of latent fingermarks on Euro banknotes. The exercise focused on two denominations (€10 and €50) to investigate the impact of substrate characteristics, particularly the presence of a protective coating, on fingermark visualisation. Each test consisted of five fingermarks deposited in different areas of the banknotes. Three fingermarks were naturally deposited by a single donor and two marks were deposited using a fingerprint stamp and artificial secretions. Thirty-seven laboratories across Europe participated to the visCE. Participants were asked to process banknotes using their routine detection sequences, and to submit their results, images, and reagent formulations for evaluation. Twenty distinct detection sequences were reported, reflecting a marked lack of standardisation across laboratories. Amino acid reagents performed well on the unvarnished €50 banknotes but showed reduced efficiency on the varnished €10 notes, where CA fuming and other techniques suited to non-porous substrates yielded superior results. Analysis of the submitted formulations revealed notable variability, with several recipes deviating from established references. Significant inconsistencies were also observed in imaging and observation conditions, including issues with exposure, sharpness, and resolution, which adversely affected the quality of otherwise well-developed fingermarks. Based on the findings, recommended sequences were identified for each denomination: PRELIM → CA → BMP → VMDAg/Zn for varnished €10 banknotes and PRELIM → IND/Zn → NIN → PD for unvarnished €50 banknotes. The results underscore the need for greater harmonisation in detection workflows and imaging practices and will inform future ENFSI initiatives aimed at improving standardisation and reproducibility in fingermark detection across Europe.