<P> Freshly dried bloodstains are a glossy reddish - brown in color . Under the influence of sunlight, the weather or removal attempts, the color eventually disappears and the stain turns gray . The surface on which it is found may also influence the stain's color . </P> <P> Crime scenes are normally carefully searched for blood residue . Flashlights held at an angle to the surfaces under examination assist in this, as do luminol sprays which can detect even trace amounts of blood . Presumptive tests exist with which blood can be distinguished from other reddish stains, such as of ketchup or rust, found at the scene . The search includes areas beyond the immediate crime scene where blood might have been wiped off or bloody fingerprints left, such as towels or doorknobs . At outdoor crime scenes, bloodstains may be recovered from the ground or from plant surfaces . </P> <P> 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 . Recently 3D imaging techniques have been tried for documenting and investigating bloodstains . </P> <P> To collect samples for analysis, wet blood is collected with a syringe and stored in a tube with anticoagulant, or collected with absorbent fabric that is allowed to air - dry . Dried blood is scraped off with a blade, or collected with a moistened cotton - tipped applicator, a gel lifter or fingerprint tape . Bloodstained clothing and other items are generally wrapped in paper and shipped whole to the laboratory . To prevent deterioration, blood residue samples are stored under refrigeration and, in the case of stains, air - dried . </P>

Who developed a way to identify dried blood