Case 173
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.
Avery
“Lane and Frankie are both innocent.”
Lane
“Neither Avery nor Drew is guilty.”
Drew
“Neither Avery nor Lane is guilty.”
Morgan
“Either Drew or Frankie is guilty.”
Frankie
“Either Drew or Morgan is guilty.”
Who is guilty?
Solution: Morgan
If Morgan is guilty, Morgan's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.