Coomassie brilliant blue: an excellent reagent for the enhancement of faint bloody fingerprints

Abstract

Bloody fingerprints are an important subclass of fingerprint evidence that often requires chemical enhancement. Five bloody fingerprint enhancement reagents were evaluated in this study. Acid yellow 7, water-based amido black, coomassie brilliant blue, leucocrystal violet, and leucocrystal violet followed by methanol-based amido black, were tested for their ability to enhance fingerprint detail. Bloody fingerprints were prepared on porous surfaces: paper and raw wood; semi-porous surfaces: painted drywall and polyurethane treated wood; and non-porous surfaces: plastic, glass, metal, and tile. Coomassie brilliant blue, leucocrystal violet, and leucocrystal violet followed by methanol-based amido black were determined to be the best reagents for the enhancement of patent fingerprints made from blood diluted 1:5 on porous and semi-porous surfaces, while water-based amido black was the best reagent to use for fingerprints on non-porous surfaces. Coomassie brilliant blue was found to be the best reagent for the enhancement of faint fingerprints made from blood diluted 1:25 on porous and non-porous surfaces, while none of the reagents produced good quality fingerprints on semi-porous surfaces. Only acid yellow 7 and coomassie brilliant blue effectively enhanced latent fingerprints made on tile from blood diluted 1:125. Our results show that coomassie brilliant blue is an effective reagent for the enhancement of faint or latent bloody fingerprints on a wide variety of porous and non-porous surfaces.