Case 075
The Swapped Envelope
A sealed envelope was replaced with an empty one.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Rowan
“Neither Finley nor Parker is guilty.”
Noah
“Parker is guilty.”
Cameron
“Rowan is innocent.”
Finley
“Neither Cameron nor Parker is guilty.”
Parker
“Finley is innocent.”
Who is guilty?
Solution: Noah
If Noah is guilty, Noah's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.