Detection of Latent Fingerprints on Non-Porous/Semi-Porous Surfaces with Cu/Ag Coatings:A Forensic Science Study

The latent fingerprint,left on non-porous and semi-porous surfaces,was imaged with vacuum evaporated metal-coatings.The influence of the type and thickness of coatings,including Ag/Cu/Au/Zn metals and CuZn/AgZn/AuZn alloys,on the image quality of fingerprint was investigated for cost-efficiency optimization.The results show that depending on specific situations,a proper coating works better for a proper fingerprint.For instance,the optimized thickness of metal coating should be greater than that of alloy coating;when it comes to image quality of fingerprint on plastic surfaces,a descending order existed:CuZn>AuZn>AgZn;Cu and Ag coatings work well for fresh fingerprints on plastic surface,and in imaging fingerprint on dark colored PE membrane,especially fingerprint with retention time of 30-days,Ag-coating outperforms AuZn-coating because of higher resolution and greater contrast.