Case 230
The Vanished Key
A locked evidence cabinet was opened without permission.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Reese
“Neither Dakota nor Quinn is guilty.”
Dakota
“Riley is innocent.”
Riley
“Neither Reese nor Dakota is guilty.”
Quinn
“Reese is innocent.”
Rowan
“Quinn is guilty.”
Who is guilty?
Solution: Rowan
If Rowan is guilty, Rowan's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.