How do blood tracker flashlights work to help see a blood trail at night?

Answer by  quisqualis (1756)

They have ultraviolet light bulbs, which can detect blood, if the blood has been sprayed with a special chemical. The chemical combines with components in blood, and the result is a blood stain that glows when UV light is on it. Without the chemical, the UV flashlight won't find blood.

Answer by  y3636363 (1380)

They basically shine down on the ground and you can see the red spots. It glares on to the trail.

Answer by  Amber40 (24961)

They use colored film or certain colored led lights to help the blood stand out. The different hue of the light makes the red color of the blood more noticeable.

Answer by  diva25 (4016)

I remember reading that they run on black lights. They work better at night because it is dark and it is easier to use a black light in the dark.