Case 288
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.
Logan
“Neither Rowan nor Emery is guilty.”
Kai
“Either Emery or Parker is guilty.”
Rowan
“Logan and Parker are both innocent.”
Emery
“Neither Rowan nor Parker is guilty.”
Parker
“Rowan is innocent.”
Who is guilty?
Solution: Kai
If Kai is guilty, Kai's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.