Development of Latent Fingermarks on Various Surfaces Using ZnO-SiO2 Nanopowder†

Fingermarks are one of the most useful forms of evidence in identification and can provide generalized proof of identity in crime investigation. They are developed using various conventional powders. The novel nanopowder ZnO-SiO2 was synthesized via the conventional heating method and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy-dispersive X-ray (EDX) analysis, transmission electron microscope (TEM), and X-ray diffraction (XRD). The mean particle size of ZnO-SiO2 nanopowder calculated through TEM was 32.9 nm. The development of fingermarks was carried out by powder dusting and small particle reagent (SPR) methods. Powder dusting method was used for the development of latent fingermarks on various dry, nonporous, and semi-porous surfaces. The SPR method was also applied to wet nonporous surface. The developed latent fingermarks using ZnO-SiO2 nanopowder were found to have excellent quality with very clear third-level ridges detail and had better visibility than commercially available white powder.