Case 286
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.
Casey
“Alex and Sam are both innocent.”
Alex
“Sam and Peyton are both innocent.”
Sam
“Either Peyton or Quinn is guilty.”
Peyton
“Neither Alex nor Sam is guilty.”
Quinn
“Peyton is guilty.”
Who is guilty?
Solution: Quinn
If Quinn is guilty, Quinn's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.