Case 324
The Stolen Watch
A valuable watch disappeared during a private gathering.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Parker
“Blake is innocent.”
Quinn
“Parker is guilty.”
Blake
“Parker and Frankie are both innocent.”
Frankie
“Either Quinn or Dakota is guilty.”
Dakota
“Neither Parker nor Blake 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.