Fingermark development and visualisation methodologies on ‘vegan’ and Covid-19 preventive leather substrates

Leather exhibits (purses, belts, phone cases) are frequently encountered in investigations of diverse criminal offences (homicide, sexually motivated, acquisitive) and both natural and civilian mass disasters. Their recovery from the incident scene can be pivotal to identification of persons who have handled them. This process may be hindered by the complexity of leather surfaces due to variations in permeability, porosity, colour, texture and animal origin. The challenge is heightened by the United Nations 17 Sustainable Development Goals and COP26, which highlight environmental concerns over the sustainability of fashion textiles and their production, including genuine and synthetic leather. This has resulted in an increasing array of fungi-, bacteria-, and plant-based ‘vegan’ alternatives. Here we present, our initial investigation using innovative Zeiss Smart Zoom dark light digital microscopy and scanning electron microscopy, to determine the topographic and cross-sectional analysis of these novel substrates, as well as footwear leather substrates with a unique Covid-19 preventive surface coating. Subsequently, latent fingermarks on these novel substrates and conventional surfaces, were visualized using development methodologies, including powder suspension and cyanoacrylate fuming / BY40 exposure followed by fluorescence imaging. Identifiable fingermarks (aged for 28 days) were successfully obtained and statistical analysis of these will be discussed. This research will be of the utmost interest to practitioners within chemical development laboratories, undertaking fingermark examinations on leather, in furthering the knowledge of this challenging substrate.