Case 296
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.
Blake
“Neither Marley nor Finley is guilty.”
Marley
“Neither Finley nor Jules is guilty.”
Riley
“Either Blake or Jules is guilty.”
Finley
“Riley is guilty.”
Jules
“Neither Blake nor Marley is guilty.”
Who is guilty?
Solution: Riley
If Riley is guilty, Riley's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.