[ccwoman]

LEUCOCRYSTAL VIOLET
(LCV) A new positive blood identifier that turns permanent VIOLET when in contact with blood. Leucocrystal violet can be testified to in court as a blood identifier at the scene without further testing to identify the stain as blood.

[newgeezer]

The caption in the photo gallery says, "The violet-colored markings indicate locations where authorities searched for blood."

As I look at the photos, I can't imagine all those violet markings testify to the presense of blood. I suspect the marker looks different (brighter, perhaps?) when blood is detected. The violet areas in those photos just seem too uniformly large and round for all of them to be indicating the actual presense of blood.

Just my opinion, of course.