Can't recommend this book highly enough. Every thriller writer must read it and own it. Hell, anyone writing about police officers in any capacity must read it. Aside from covering the correct police procedures (the way they are performed in real life as opposed to what we're used to seeing on TV), you'll learn about blunders to avoid. For example, a detective never returns to the crime scene to collect more evidence: once they're done with it, they're done. And they don't investigate a crime on their own after getting suspended (what I had in my plot and will now change)—if they do, they most likely get fired. You'll also find out what happens to a body of someone murdered after it was found, and what happens to a body of a killer when they're being electrocuted—what it looks and sounds and smells like. Grim but very accurate details.