An Investigation into a Sprayable Application of Oil Red O for Fingerprint Analysis

Oil Red O (ORO) which has been historically used as an immersion solution in forensic science crime laboratories can be reformulated into a sprayable solution for more flexible use including at crime scenes. The aim of this study was to replace the methanol in the original solution with a safer alternative for the sprayable technique, Isopropyl Alcohol. As well as use this formulation to develop a technique for utilizing the solution in a portable airbrush. Additionally, the sprayable formulation excluded Sodium Hydroxide, a strong base, to decrease the pH. Two different processing methods were tested on a random sample of fingerprints: the sprayable solution and the sprayable solution then subsequent processing with the traditional immersion Oil Red O technique. Samples were taken on a variety of porous substrates: copy paper, manila folder, and check paper that were then stored for between 2-6 hours to mimic a crime scene scenario or 1 week. Samples that were stored for 1 week were additionally subdivided and purged with nitrogen to remove oxygen, microbes, and bacteria in order to better preserve the quality of the print.