NCJ Number
237605
Date Published
2011
Length
11 pages
Annotation
This paper describes the Fluorescein Method as a presumptive blood test for latent bloodstain detection, and a protocol is presented for the appropriate steps in using this method.
Abstract
Fluorescein is highly sensitive to the hemassociated molecules (enzymes and iron) in the red blood cells. Traces of these hemassociated molecules will embed themselves on substrata even after multiple cleaning. Fluorescein can also be used to discover and enhance shoe tracks leading from a bloody crime scene, thus allowing investigators to follow the suspect's trail based on the detection of latent bloodstains from the shoes. In reacting to the proteins and iron ions in the hemoglobin, Fluorescein will fluoresce when exposed to light at 420nm to 485nm wavelengths that peak at approximately 460-480nm. The method requires either a forensic light source, which can be light-emitting diodes, alternate light source, strong ultraviolet light, barrier filter (deep yellow or orange), and a 1.5 to 3 percent solution of hydrogen peroxide. Fluorescein can be applied with a spray bottle, garden pump sprayer with a fine-mist sprayer tip, or similar spraying equipment. As with luminol, fluorescein must be applied in a darkened room or at night. Ambient light must not be so strong as to overpower the fluorescent reaction. Research indicates that Fluorescein will not affect DNA analysis; however, if a thickener is used, it is best to indicate this on any DNA samples collected, since this can lead to complications with the automated DNA extraction process. Fluorescein use is appropriate under the following conditions: an older crime scene, a recent crime scene with signs of cleaning, a crime scene where blood evidence is difficult to see due to substrate color, where blood has been diluted by rain, and when clothing has been laundered. 19 references