Visualization of latent and depleted fingermarks on CDs and DVDs using columnar thin films

Abstract

CDs and DVDs are forensically important substrates for latent fingermarks. To enhance the visualization of fingermarks on CDs and DVDs, columnar thin films (CTFs) of either nickel or chalcogenide glass were deposited. The CTFs were deposited by directing a collimated vapor flux towards the substrate placed at an angle and made to rotate rapidly. The resulting CTFs of upright columnar morphology were grown conformally over these substrates. This process was shown to significantly enhance the visual quality of fingermarks. The fingermarks were aged for either 24 h or 72 h prior to the deposition of the CTF and both the latent and depleted fingermarks were used. Enhancement to maximum possible grade for visual quality occurred, even for the samples that were developed three days after the fingermarks were placed on them.