Development of an electrostatic charge device for visualisation of latent fingerprint on bullet cartridges and curved metal surfaces

• Main Author: Fong, Derren Keng Mun.
• Other Authors: Seah Leong Keey
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Manufacturing::Product engineering
• Online Access: http://hdl.handle.net/10356/40303
• Institution: Nanyang Technological University

Crime is an existent social problem which is a concern of many people. It is necessary to identify and punish the perpetrator, to prevent a possible string of crimes from occurring. Fingerprint identification is an effective method of solving or preventing crimes from taking place. The uniqueness of the fingerprints allows police officers to make use of this singularity to catch criminals, making fingerprints an integral part of law enforcement process. An in-depth research on latent fingerprints is conducted, as they are not readily visible on surfaces, and must be enhanced or developed to be seen fully and collected. One of the objectives of this study is to analyze the latent fingerprints obtained on brass cartridges and curved surfaces. The other objectives are to find out the optimum electrostatic conditions for the enhancements of latent fingerprints, and also to investigate the extent to which the sweat of different individuals can cause corrosion on curved metallic surfaces. The experiments are conducted with close reference to the live firing conditions of an M16 rifle, and the usual time frames the police take to find the expended bullet cartridges. From the experiments conducted, it can be seen that corrosion of the brass cartridges are affected by the different sweat compositions and temperatures. The remains of matter present in fingerprints also depend on the temperature involved. The ability of visualizing the fingerprints depends on factors such as the type of powder used, the voltage applied as well as the pressure applied. Also, the experimental results showed that different dietary intakes can cause variations in the sweat compositions of people, resulting in different degrees of corrosion. In conclusion, sweat can tell the investigators more about the individual rather than identification. Fingerprint samples must be taken with care as it can vary with pressure applied and skin conditions of the donor. A wider range of heating temperatures, test materials, and environmental conditions can be used to identify trends for better understanding of sweat composition, corrosion and the electrostatic enhancement method.