The use of longwave reflected UV imaging for the enhancement of cyanoacrylate developed fingermarks: A simple, safe and effective imaging tool.

Longwave ultraviolet reflection (LWUVR) imaging is reported as a simple, safe and non-invasive technique that significantly aids in the visualisation of cyanoacrylate developed latent fingermarks. The process can precede traditional cyanoacrylate dye staining and often removes the necessity to use these chemical contrast reagents, saving time, cost and eliminating mess. The non-destructive nature of the process and high resolution images that are obtained, builds upon issues that surround shorter-wavelength UV imaging. It has been demonstrated that, for most samples tested (a range of non-porous and semi-porous evidence), LWUVR imaging provided superior or similar results to those obtained using the traditional BY40 dye stain. The lack of penetration depth by LWUV radiation means that only the features of the surface under observation is detected by the camera, meaning that interference that may otherwise arise from fluorescence on the reverse side of the evidence (BY40 or fluorescent inks) under conventional fluorescent dye stain imaging modes, is mitigated. A new sequential processing workflow is proposed that does not impede with the conventional and widely adopted fume>stain>fluorescence sequence, but in fact allows LWUVR imaging to be conducted in a manner that serves to benefit the sequence and, ideally, save time during the examination and treatment of evidence.