Development of environmentally insulted fingermarks on nonporous forensically relevant substrates with conformal columnar thin films

A systematic study was undertaken on the influence of environmental insult on the efficacy of developing a latent fingermark on a nonporous substrate by the deposition of a conformal nanoscale columnar thin film (CTF) on it. Four warm-weather and one cold-weather environmental conditions were chosen as representative for Pennsylvania. Three durations of environmental insult were selected: a day, seven days, and 30 days. Fingermarks were collected from one male donor and one female donor on five different types of substrates. The evaporant material for the deposition of a CTF on a specific fingermark sample was specifically chosen based on a prior study. Photographs of every fingermark were graded for quality after collection, after enduring the chosen environmental insult for a particular duration, and after CTF development. The results of the study on 750 fingermark samples indicate that environmental insult does not always degrade and can even improve the quality of fingermarks, and CTF deposition thereafter may considerably enhance the insulted fingermarks for visualization.