Case 048
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.
Elliot
“Neither Taylor nor Parker is guilty.”
Taylor
“Elliot and Parker are both innocent.”
Finley
“Either Taylor or Drew is guilty.”
Parker
“Elliot and Drew are both innocent.”
Drew
“Either Elliot or Finley is guilty.”
Who is guilty?
Solution: Finley
If Finley is guilty, Finley's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.