Deposição eletroquímica de partículas de prata aplicadas na revelação de impressões digitais latentes em superfícies metálicas

Abstract

Fingerprints and several other traces found at a crime scene participate in a group of traces that must be analyzed to help clarify the criminal fact. One of the most common procedures in forensic practice is the development of latent fingerprints (LFP), which are crucial for visualizing fingerprints and using them as a primary source of identification for individuals. In this context, the development of fingerprints using electrochemical methods on metal surfaces has shown great potential. The purpose of this study is to conduct a brief investigation into the process of depositing silver (Ag) using the potentiodynamic (PDN) and potentiostatic (PST) methods in an electrochemical system with silver nitrate (AgNO3 5x10-³ mol/L) and potassium nitrate (KNO3 5x10-³ mol/L) solutions, a platinum counter electrode and Ag/AgCl (KCl sat.) as a reference electrode. Additionally, the study aims to facilitate the detection of recent and aged LFP using the PST method (E = - 0.35 V vs. Ag/AgCl (KCl sat.)) on steel, brass, and copper plates, as well as on objects like cartridge cases (brass), keys, and coins. The results were evaluated using international protocols established in the scientific community. Out of the 42 stainless steel, brass, and copper plates, 89.7% of the samples showed strong development of fingerprint details, achieving the highest scores in the classification system. Similarly, out of the 41 cartridges, 98.29% of the samples showed strong details development. All the fingerprint developments achieved high levels of quality and were analyzed using forensic software. The software easily recognized various characteristic fingerprint patterns such as fundamental type, bifurcations, core, delta, and ridge ending. The development of latent fingerprint processing on keys and coins showed great potential for application on everyday metal objects. The results suggest that Ag electrodeposition is an innovative and sensitive methodology to develop LFPs on different metallic substrates, the Ag film showed good uniformity and adhesion to the surfaces and was efficient in producing contrast between surface and fingerprint in recent and aged samples.