Case 121
The Missing File
A signed contract file vanished from the archive.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Marley
“Either Parker or Morgan is guilty.”
Parker
“Neither Harper nor Taylor is guilty.”
Morgan
“Either Marley or Harper is guilty.”
Harper
“Neither Morgan nor Taylor is guilty.”
Taylor
“Parker is innocent.”
Who is guilty?
Solution: Marley
If Marley is guilty, Marley's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.