Case 317
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.
Kai
“Blake is guilty.”
Morgan
“Either Kai or Blake is guilty.”
Jordan
“Morgan and Blake are both innocent.”
Finley
“Neither Jordan nor Blake is guilty.”
Blake
“Neither Jordan nor Finley is guilty.”
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.