A Comprehensive Review of Small Particle Reagent Efficacy in Developing Latent Fingerprints Immersed in Water: An Empirical Analysis

A latent fingerprint is a shred of inevitable evidence left on a scene of the crime by the offender. Being aware of fingerprints, offenders tend to deteriorate all possible pieces of evidence by different methods that include burning, immersing the evidence in water, and many more. Water-immersed latent fingerprints are still viable for the development process due to the presence of water-insoluble components (Lipids, oils, etc.) in the latent fingerprint. Different methods have been tested for the imaging of water-immersed latent fingerprints among which Small Particle Reagent (SPR) was found to be the most efficient by many researchers. This method involves the application of fine particles suspended in a reagent based liquid medium onto the surface containing latent prints immersed in water, resulting in the development of highly detailed fingerprint impressions. The reagent comprised of hydrophobic head and hydrophilic tails that adhere to latent fingerprint and suspended particle respectively and thus act as a junction among them. The diverse composition of Small Particle Reagent, various surfaces for taking impressions of latent fingerprint (followed by immersing in water), the Shelf life of SPR, immersion time of latent fingerprint, and various immersion medium studied by researchers has been reviewed in this paper. The maximum shelf life of SPR reported by a researcher is 6 months and the maximum immersion time is 45 days. Furthermore, the need for green synthesis of SPR is emphasized due to its toxicity caused by long-term exposure.