From nanomaterials to macromolecules: Innovative technologies for latent fingerprint development

The majority of conventional techniques for latent finger print enhancement are based on chemical reactions or interactions between the developer and fingermark residue components, providing contrast between the surface and the fingerprint ridges. However, these methods might be limited by factors associated with particle size, toxicity of the reagent, selectivity, or sensitivity, that may be circumvented by the synthetic design of innovative materials based on nanoparticles or macromolecular materials, such as conducting polymers,applied as latent fingerprint developers on different surfaces and conditions. Since the structural, optical and electronic properties of the material can be tailored by its molecular scale, the size control of the developer plays an important role to improve the interaction with the latent fingermark residue and/or the surface, enhancing the color contrast and the quality of the developed image (or dactylogram). Hence, creating new reagents and strategies to apply nano- and macromolecular scale materials as latent fingermark developers constitutes an exciting rapidly expanding area, generating a wealth of new materials that lead to forensic methodologies with enhanced performance. Recent progress in the application of such materials for development of latent fingermarks present on different surfaces and subject to complex circumstances will be discussed. This will focus on the main barriers to making nanoparticles and conducting polymers viable—and occasionally preferred—materials routinely used by forensic experts, and the potential advantages over conventional methodologies in the acquisition and analysis of crime scene evidence.