Oh, and speaking of black lights, I'm about to ruin every single detective show on TV for you right now. Ready? Here we go: Black lights don't detect blood. Well, they do, but not in the way TV depicts it. In college we had a session where my instructor took several fabrics and smeared various bodily fluids on them (forensics courses are ... interesting). Then she took us into a dark room and had us shine black lights on them, and that's when we discovered that blood absorbs UV light and appears as black splotches. So what's that bright, glowing fluid all the TV black lights are revealing? The answer, of course, is semen. Every single episode of CSI: Miami features David Caruso standing in a room absolutely drenched in man-batter.