A proof-of-concept study of the use of commercially available cashew gum powder as latent fingermark developer

Latent fingermarks developed at crime scenes are essential pieces of evidence in investigations. However, many of the techniques used in this process are hazardous to the health of examiners. Therefore, it is desirable to search for less toxic, environmentally friendly, and cost-effective approaches. A promising alternative in this regard is the use of cashew gum powder as a latent fingermark developer. This material was compared in detail with the white development powder routinely employed by the Brazilian Federal Police. For this purpose, natural, eccrine, and sebaceous fingermarks in depletion series, regular and split fingermarks from different donors, on different surfaces, were evaluated according to the CAST and UC scales. The evaluation process was performed by volunteers (both experts and laypersons) and the results were statistically analyzed. Furthermore, to understand the structural and physicochemical properties of cashew gum powder, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis absorption and Fourier-transform infrared spectroscopy (FTIR) were used. With a regular size distribution, flake shape, hydrophilicity, and presence of different functional groups responsible for adhesion to the residues present in latent fingermarks, cashew gum powder proved to be superior to the regular white powder for the conditions tested. This finding could mean the discovery of an affordable, non-toxic, and effective new material for latent fingermark development.