Detection of latent fingerprints on metal surfaces by aqueous electrolyte gel

Abstract

Latent fingerprints are the important forensic evidence usually recovered from crime scenes. One of the most difficult surfaces to develop for latent fingerprints is metal surfaces. The objective of this research was to develop an aqueous electrolyte gel for the detection of latent fingerprints on metal surfaces.  Aluminum, stainless steel, brass, and alloy sheets were selected in this study.  In the experiment, several formulae of electrolyte gel (potassium permanganate, calcium chloride, and silica powder (PCS gel)) were prepared and used for recovering latent fingerprints on those surfaces. Good quality fingermarks could be observed on all of the metal surfaces after using the PCS gel made from the mixture of 5 mL of 5% w/v potassium permanganate solution, 5 mL of 1% w/v calcium chloride solution, and 5 g of silica powder. The results demonstrated that the PCS gels developed in this study may be used to detect latent fingerprints on various types of metal surfaces in authentic forensic samples.