Case 085
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.
Morgan
“Neither Frankie nor Reese is guilty.”
Drew
“Reese is guilty.”
Frankie
“Morgan and Casey are both innocent.”
Reese
“Neither Morgan nor Frankie is guilty.”
Casey
“Morgan is innocent.”
Who is guilty?
Solution: Drew
If Drew is guilty, Drew's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.