Case 253
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.
Drew
“Morgan is guilty.”
Morgan
“Jordan is innocent.”
Parker
“Either Drew or Morgan is guilty.”
Jordan
“Morgan and Peyton are both innocent.”
Peyton
“Parker and Jordan are both 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.