Comparison of WET UCIO powder suspension and novel luminescent techniques for latent fingermark detection on the adhesive side of tape

Abstract

Pressure-sensitive adhesive tapes are a common vector for latent fingermarks in forensic investigations, often detected using powder suspension techniques. Among these, WET UCIO, employed by the Mossos d’Esquadra Central Fingerprint Development Laboratory Scientific Police Division in Catalonia, Spain, is a carbon black powder suspension method showing promise for casework. WET UCIO also utilises a cost-effective detergent solution, enhancing its practicality and sustainability. While powder-based methods like WET UCIO have proven effective, there is growing interest in luminescent techniques, such as exfoliated Egyptian blue (EB) and CuInS₂/ZnS (CIS/ZS) quantum dots (QDs), which have been successfully tested on non-porous surfaces. This study investigates the operational efficacy of WET UCIO on adhesive tapes, demonstrating its strong performance on various substrates, including dark-coloured surfaces. Additionally, luminescent techniques featuring EB and CIS/ZS QDs are explored, offering valuable insights into their potential effectiveness for forensic analysis. The performance of the WET UCIO and luminescent techniques were assessed using both deliberately placed fingermarks, and also an approach that generates incidental marks to better reflect operational casework scenarios.