Writer's Digest, probably best known for its magazine, also produces a series of "HowDunit" books to assist authors in accurately reflectin gpolice procedures and poisoning methods in their writings.
As a cozy mystery writer with an amateur sleuth protagonist, I probably won't include much of the information in Police Procedure and Investigation in my own books, but the book is a fascinating read, nonetheless. I just finished the chapter on fingerprinting and how police officers use the IAFIS database system to identify the individual to whom the prints belong. You can see this method in action on various cop shows ranging from CSI to Fringe. However, as Police Procedure and Investigation points out, the detectives on these shows enter the fingerprints into the system and within five seconds, the perpetrator's picture, usually a mug shot, pops up on screen with his name, last known address, and favorite dessert.
In actuality, IAFIS doesn't return the hit in mere seconds. On a good day, the detective might get a list of hits back in as few as ten minutes, with "hits" being the key word. According to the book, IAFIS provides a list of the most probable matches, not just one definite match. While this reality doesn't work well for an hour TV show (forty-three minutes without the commercials) or an action movie, where time is always the enemy and the world must be saved before the closing credits, such a method opens up endless possibilities in the book world.
Imagine your detective receiving five potential matches for a print found at a murder scene. He or she must then track down each name, one at a time. Every visit can eliminate a suspect or the visit might create even more questions as to the suspect's involvement in the crime. As the list shortens, the tension rises, until the detective has narrowed the list to only one possible person. Case solved!
Or, better yet, that final suspect might be indisputably innocent after all. The detective must revisit the list to determine what he missed or how he was duped. Only after uncovering his mistake does he discover the true identity of the killer. All that plot from just one little fingerprint.