Simple improvement in latent fingerprint detection with Ninhydrin/water glue on thermal paper

Abstract

Thermal paper is a special type of paper that is coated with chemicals on the paper layer to change color when exposed to heat. When discovering fingerprints by using chemical reagents such as ninhydrin solution with thermal paper, it shows black staining background on the heat-sensitive front side. Thus, the latent fingerprints cannot be discovered. In this study, we have reported the first utilization of ninhydrin with water glue in different ratios for the development of latent fingerprints on the thermal papers. The results showed that at 0.020-0.060 g/mL of water glue in ninhydrin solution reduced the black strain after tested with thermal paper and made the appearance of the fingerprint more clearly. So, the detectable minutiae can be used for visualization and identification of latent prints. Using an Automated Fingerprint Identification System (AFIS), it is showed between 59-87 points of minutiae. As the results, this method could be used as an alternative method to developing latent fingerprints with non-hazardous materials, reduce costs and easy to find.