If you're interested, as a matter of work or play, in police procedure, or if you enjoy the show Castle, do yourself a favor and head over to Lee Lofland's blog, The Graveyard Shift. With an easy and funny style, Lee lifts the crime scene tape and lets us see what it's like on the other side. In recent posts I've learned about homicide investigation do's and don't's and various kinds of murder charges. He also does a weekly post honoring fallen law enforcement officers. I'll soon be ordering Lee's book, Police Procedure & Investigation: A Guide for Writers. It's part of the exceptional Howdunit series of books. I used to have the volume on poisons but it freaked me out to know how many common things can kill you so I donated it somewhere, heh.
And if The Graveyard Shift whetted your appetite, I know of no bigger or more organized resource for online crime than In Reference to Murder, assembled and curated by BV Lawson. From forensics and money laundering to blogs and books, it's like a toy store. A really depraved toy store, in a good way.