Enhancing fingermark visualisation on pangolin scales and rhino horns using cyanoacrylate fuming and vacuum metal deposition techniques

Fingermark analysis is a relatively underexplored area in wildlife forensics, partly due to the complex surfaces of evidence, which often have varying porosities and textures. There is a limited amount of literature exploring cyanoacrylate fuming (CAF) and vacuum metal deposition (VMD) for latent fingermark enhancement in wildlife crime. This research addresses the scarcity of current findings by applying VMD and cyanoacrylate fuming on pangolin scales and rhinoceros horns. Using different metal depositions, an optimal VMD method has been identified to enhance latent fingermarks on a rhinoceros horn and pangolin scales successfully. Findings demonstrate that manual deposition is significantly more efficient than automatic deposition for enhancing fingermarks. In addition, Gold/Zinc (Au/Zn) VMD coupled with sequential CAF was the most effective technique, within these investigations for fingermark enhancement on pangolin scales. Au/Zn VMD was found to be most effective on the interior areas of the rhino horn, though fingermarks grade ≥ 3 were also obtained from the exterior region of the rhino horn. CAF alone was found to be effective at visualising fingermarks on pangolin scales and rhino horn. A secondary dye staining step with BY40 or R6G was successful on the non-porous pangolin scales, but dye staining significantly reduced the quality of marks on the porous rhino horn. This study offers valuable insight into using VMD and CAF coupled with sequential techniques for fingermark analysis on wildlife samples. This novel area of research can assist in the identification of perpetrators and support criminal prosecutions to protect and preserve endangered wildlife.