Time is Money or Money is Time? A Rapid Operational Sequence for Detecting Fingermarks on Polymer Banknotes

Banknotes are often found in high-profile crimes such as armed robberies, bribery, and terrorist activity. However, such exhibits present a challenge to forensic operatives regarding fingermarks development, due to their mass quantities, potential for fingermarks on both sides, and their unique complex background in terms of color, irregular patterns, and topography. Hence, the standard development protocols become inefficient, due to the difficulty in achieving high contrast images over the background. This study focused on finding an operational sequence that would minimize the time of work on polymer banknotes, in terms of both development and image processing. Thirty-two fingermarks were developed by vacuum metal deposition (VMD), black magnetic powder, and cyanoacrylate fuming (CA) followed by visualization and imaging by reflected short-wave UV (RUVIS) (96 in total), showing a distinct advantage to the CA and RUVIS imaging over the other two techniques with a 75% success rate in the dark and high background regions, due to its physical principle which neutralizes high background interference. The images were then scanned by the automatic fingerprint identification system (AFIS) to test its ability to correctly differentiate false background features from real ones, again, showing a superiority of the RUVIS with 63% of the total initial marked features, being real. Overall, the CA and RUVIS sequence was found to be an ultimate method for multiple, same-type surfaces, with the RUVIS capable of visualization and capturing of the images simultaneously, significantly reducing the time of development and image processing.