Case 361
The Stolen Prototype
A prototype vanished from a secured workroom.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Drew
“Quinn is guilty.”
Marley
“Drew and Alex are both innocent.”
Morgan
“Either Drew or Quinn is guilty.”
Quinn
“Either Drew or Alex is guilty.”
Alex
“Neither Drew nor Marley 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.