S19, E2: Rick Devon's (guest star Bradford Cover) body is found murdered in a park, and his death is automatically assumed to be drug related. Upon investigation, detectives Cyrus Lupo (Jeremy Sisto) and Kevin Bernard (Anthony Anderson) stumble upon a key in a nearby bathroom that could potentially have been left behind by the killer. Prints on the key lead the detectives to former felon, Diego Cardenas (guest star Carlos Leon), who has cleaned up his act and now works at a home for mentally challenged adults. After questioning Diego, the detectives discover a hidden relationship between the murder victim and another resident of the home, Pete Haynes (guest star Michael Rispoli). Rick and Petes relationship guides the detectives to uncover a painful family secret that could expose the killer. S. Epatha Merkerson, Sam Waterston, Linus Roache and Alana De La Garza also star.