I'm sure all writers have an extensive library of writing and forensic books. Pick one favorite from your collection and tell us the name of the book, the author, and why you think it's a valuable tool for a writer to have. I'm sure we'll all discover a new book or two for our own libraries.
Since I've said that we can only pick one, I'll start with one of my favorites.
Forensic For Dummies, by D.P. Lyle is filled with easy-to-understand information from checking for fingerprints and DNA, to investigating crime scenes and understanding the various stages the body goes through at death.