Turin Shroud blood stain. Different imaging techniques used to study a small blood stain found on the Turin Shroud, said to be the death-shroud of Jesus Christ. The techniques used are: visible light (upper left) and ultraviolet light (lower left). Under ultraviolet light, the blood serum becomes fluorescent. At upper right, the two images are combined. At lower right, cross-polarized light shows the dried crust of blood in red. The Turin Shround, kept in Turin, Italy, has been revered by the Christian church for centuries, but its origins are disputed.