In forensic science, blood residue can help investigators identify weapons, reconstruct a criminal action, and link suspects to the crime.
Flashlights held at an angle to the surfaces under examination assist in this,[1] as do luminol sprays which can detect even trace amounts of blood.
[4] The standard documentation of blood residue includes photographs and descriptions of form, color, size and position of each stain found.
Overall photographs and sketches are also produced to show the relationship of the blood residue to other elements of the scene and to enable pattern analysis.
Dried blood is scraped off with a blade, or collected with a moistened cotton-tipped applicator, a gel lifter or fingerprint tape.