Case 120
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.
Peyton
“Either Frankie or Taylor is guilty.”
Jules
“Taylor is innocent.”
Marley
“Either Peyton or Jules is guilty.”
Frankie
“Either Peyton or Taylor is guilty.”
Taylor
“Marley is innocent.”
Who is guilty?
Solution: Peyton
If Peyton is guilty, Peyton's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.