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.

Sunlight-activated near-infrared phosphorescence as a viable means of latent fingermark visualisation.

The chromium-doped zinc gallogermanate, Zn3Ga2Ge2O10:0.5%Cr3+, was prepared and modified for use as a near-infrared (NIR) luminescent fingerprint dusting powder. The optical properties of this material are illustrated and have been shown to offer versatility and promise in terms of overcoming troublesome backgrounds during latent fingermark examination and imaging. The highly fluorescent NIR emission of the powder allows inherently fluorescent and patterned substrate backgrounds to be mitigated, whilst the phosphorescent nature of the material allows all conceivable background interference to be removed, whilst also constituting the first reported use of a NIR phosphor for latent fingermark enhancement and imaging.