Luminol (C8H7N3O2) is a highly sensitive blood reagent used to detect latent bloodstain evidence, usually associated with a clean up subsequent to a bloodletting event. It has successfully detected latent blood evidence over 36 months old. If blood is present a Chemiluminessence, (Low blue light) is visible. The reaction appears brighter when viewed in total darkness.
“These can detect any bloodstain which were even cleaned even after 36 months.” Helps solving crime scenes.