is very useful in detecting latent bloodstains
on surfaces and clothing, even where attempts have been made to wash blood away. After darkening the room or area suspected as much as possible, luminol is finely sprayed on the area. The luminol reagent
reacts with iron
in the hemoglobin
portion of blood, causing an electronically excited state of the luminol molecule. Bloodstained areas temporarily appear luminescent
under an alternate light source and a filter.
Practical applications of luminol are used on possible homicide weapons, evidence, and scenes. Patterns of bloodstains such as splatter direction and intensity can verify or shatter a supposed sequence of events. Blood type analysis on the blood can be used to eliminate or pinpoint suspects. The most important feature of luminol is that it detects blood unseen by the eye, such as on dark clothing or in minute amounts.