Case 241
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.
Casey
“Kendall is guilty.”
Kendall
“Parker and Sam are both innocent.”
Parker
“Kendall and Sam are both innocent.”
Peyton
“Either Casey or Sam is guilty.”
Sam
“Parker is innocent.”
Who is guilty?
Solution: Casey
If Casey is guilty, Casey's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.