Case 339
The Broken Seal
A tamper seal on a storage crate was cut overnight.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Finley
“Emery and Taylor are both innocent.”
Emery
“Casey and Taylor are both innocent.”
Alex
“Either Finley or Taylor is guilty.”
Casey
“Finley is innocent.”
Taylor
“Either Alex or Casey is guilty.”
Who is guilty?
Solution: Alex
If Alex is guilty, Alex's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.