Case 100
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.
Jordan
“Alex is guilty.”
Peyton
“Jordan is innocent.”
Alex
“Either Jordan or Peyton is guilty.”
Hayden
“Jordan and Peyton are both innocent.”
Kendall
“Peyton is innocent.”
Who is guilty?
Solution: Alex
If Alex is guilty, Alex's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.