Latent Print Detection by MacroRaman Imaging

Exposure to light or heat, or simply a dearth of fingerprint material, renders some latent fingerprints undetectable using conventional methods. The authors address detecting such elusive fingerprints using detection targeting photo and thermally stable fingerprint constituents: Surface Enhanced Raman Spectroscopy (SERS). SERS can give descriptive vibrational spectra of amino acids, among other robust fingerprint constituents, and good sensitivity can be attained by improving metal-dielectric nanoparticle substrates. To the author's knowledge, this represents the first SERS imaging of fingerprints and this work progresses toward the ultimate goal of vibrationally detecting latent prints that would otherwise remain undetected using traditional development methods. This would, therefore, significantly increase the likelihood that any print, but particularly those exposed to thermal events or light damage, would be detected. Although the enhancement factor of SERS substrates is as yet insufficient to facilitate the detection of the most difficult prints, the conclusions reached about the feasibility of SERS fingerprint detection and especially thermal and photo-degradation of prints, include useful information for improving all methods of latent detection, both traditional and novel. The ultimate success of this technique will come with the creation of a SERS enhancing reagent that offers, and retains upon dispersal to a remote surface, the power magnitude signal enhancement purported by tailor-made, in-situ advanced substrates being tested with strong Raman responders, as opposed to weaker Raman responders such as amino and fatty acids.