Case 080
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.
Frankie
“Neither Dakota nor Noah is guilty.”
Dakota
“Finley is innocent.”
Noah
“Dakota and Finley are both innocent.”
Morgan
“Frankie is guilty.”
Finley
“Either Frankie or Morgan is guilty.”
Who is guilty?
Solution: Morgan
If Morgan is guilty, Morgan's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.