Visualization of latent fingermarks on copper surfaces by metal deposition

Abstract

When the papillary lines of the skin of fingers, palms and soles come into contact with the touched surface, a fingermark is created, which can be used to identify the person who left the evidence. The quality and usability of a fingermark as evidence for identification may depend on many factors. In order to justify the research, a statistical overview of the number of investigations performed at the crime scene with evidence found in general, as well as the number of fingermarks found, was presented. Given that the number of fingermarks found at the scene of crime in the territory of the police unit for the city of Belgrade is very large, and the percentage of identification of persons based on fingerprints is in the single digits, there is space for its increase. The success of personal identification could be improved by introducing new methods for visualizing fingermarks. The paper provides an overview of existing methods for visualizing latent fingermarks at the scene, as well as a comparison of individual methods for visualizing latent fingermarks on metal surfaces, such as copper. The method of metal deposition and the method of applying fingerprint (conventional) powders, based on carbon (instant black), on a metal surface such as copper, were used. A comparison of the visualized fingermarks was performed and their quality, i.e. potential for identification of persons was determined. The application of electrochemical metal deposition for the visualization of latent fingermarks gave satisfactory results with certain limitations, including the following: it is necessary to find a fingermark on an electrically conductive substrate; it is necessary to apply the method on the equipment located in the laboratory, on condition that the object with the latent fingermark is portable and of suitable dimensions and mass so that it can be immersed in the cell for electrolysis.