In Poe's "The Cask of Amontillado", Montresor has gone to great lengths to make sure he is not caught in punishing Fortunato. Remember, that Montresor states that he must "punish with impunity." The line, "A wrong is unredressed when retribution takes over its redresser," would say to the modern reader, "If I get caught at this, then I didn't really get my revenge."
When Fortunato begins to scream, Montresor is ready to run him through with his rapier (sword), but the thickness of the walls convinces Montresor that the screams will not be heard. He follows through with his original plan and even begins screaming himself to proof his newly found confidence.