Leather Surfaces: Species Differentiation and Fingermark Visualisation

The predominance of latent fingermarks at crime scenes highlights the paramount importance of methodologies for their development and visualisation. However, despite the array of available techniques, prior exposure to varied environmental conditions with substrate surface porosity, texture and colour, are vital considerations. Leather surfaces in particular are known to be challenging and are frequently encountered in casework (footwear, clothing, restraints, vehicle interiors and wallets).

The complexity of leathers can be further sub-categorised via source (fish, mammalian, reptile), physical surface properties (embossed, smooth, textured), authenticity (faux, genuine) and chemical process finishes (dyes, patent, pearlised, waterproofing). This presentation will target fingermark development and visualisation on leather surfaces, by assessing sequential processing, environment conditions for varied timeframes and reagent delivery.

Here we present investigations involving advancements of conventional powdering and cyanoacrylate fuming application methods, using two novel reagents (PolycyanoUV and FPNatural1). Visualisation involved differing modes of interaction (excitation and emission through opposing electromagnetic spectra (UV and IR).

Additionally, we highlight the cross sectional structures and differential histological surfaces of leathers from species including: bovine, caprine, cervine, equine, ovine and porcine, via optical profiling and high power digital microscopy.

Critically, for surfaces previously deemed unsuitable, the practitioner recommendations will offer enhanced success rates. Ultimately, these results will interest international Criminal Justice System agencies in potentially assisting varied offence investigations (acquisition, wildlife crime, homicides, weapons, sexual assaults).