A modified oil red O formulation for the detection of latent fingermarks on porous substrates

A simplified procedure for the recently introduced fingermark development reagent Oil Red O (ORO) is presented. This lipid-sensitive reagent offers the potential to detect latent fingermarks on porous substrates that have been exposed to water, which is not possible using the more commonly employed amino acid-sensitive reagents. Using this modified procedure, recently deposited (less than one week since deposition) latent fingermarks were readily developed on a variety of paper types. The ability to detect fingermarks on paper surfaces that had been wetted was also demonstrated. The performance of the modified ORO procedure was found to be variable in its ability to detect fingermarks that had been left exposed to the laboratory environment for periods of time greater than one week. Comparisons with the previously reported procedure for ORO found that the proposed modified procedure produced a similar degree of fingermark development. Additionally, comparisons with physical developer (PD) found that both ORO approaches performed similarly to, or better than, PD on fresh (less than one week since deposition), charged fingermarks. However, PD was the superior method for detecting both older and uncharged fingermarks.