Case 142
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.
Alex
“Neither Parker nor Emery is guilty.”
Blake
“Either Parker or Emery is guilty.”
Parker
“Alex is innocent.”
Emery
“Neither Parker nor Cameron is guilty.”
Cameron
“Emery is innocent.”
Who is guilty?
Solution: Blake
If Blake is guilty, Blake's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.