20 Things You Didn't Know About Shutter Island

4. The Script Quotes A Real Life Serial Killer

As Teddy passes through Ward C on his way to encounter George Noyce (Jackie Earle Haley), he briefly stops to notice a patient who is painting the wall with his own blood, and who quietly whispers, "Stop me before I kill more."

This creepy one-liner wasn't written solely for the film nor Lehane's novel, though, but is in fact a reference to Chicago serial killer William Heirens who operated in the 1940s.

After murdering one of his victims, Heirens wrote on her wall in lipstick, "For heavens Sake / catch me / Before I kill more / I cannot control myself." This act of theatrical desperation also prompted him to be labelled The Lipstick Killer by the mass media.