There's a lot of unbelievable technology in cop shows and movies -- computers that can zoom in and "enhance" a tiny section of a video frame; machines that can isolate a particular background voice from a muffled recording in a matter of seconds. Most of this stuff is pure fiction, fabricated by the writers to move the plot along. But one of the most outlandish TV cop tools, a special chemical that reveals invisible blood traces, is entirely real.

In this article, we'll find out how this strange compound, commonly known as luminol, reveals hidden crime scenes. As we'll see, this chemical is just as cool as it sounds, but it does have drawbacks and limitations not usually addressed on TV.