Columnar-thin-film-assisted visualization of depleted sebaceous fingermarks on nonporous metals and hard plastics.

A fingermark on a nonporous substrate can be developed by depositing a columnar thin film (CTF) on it, but the CTF technique's sensitivity for low-quality fingermarks is unknown. The optimized CTF and traditional development of several depletion series of sebaceous-loaded fingermarks were compared using a split-print methodology as well as subjective and objective grading schemes, in a limited laboratory trial. CTF development was superior to development with selected traditional techniques on brass, anodized aluminum, black acrylonitrile butadiene styrene (ABS), and white nylon. On white ABS and black nylon, the CTF technique performed poorly but still as well as the best-performing traditional development technique. The CTF technique was more sensitive on brass and anodized aluminum than, and as sensitive on the four hard plastics and stainless steel as, the best-performing traditional technique. Thus, the CTF technique is useful to develop friction-ridge detail from limited fingermark residue on some smooth substrates.