Case 337
The Vanished Key
A locked evidence cabinet was opened without permission.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Kendall
“Neither Morgan nor Marley is guilty.”
Noah
“Neither Kendall nor Morgan is guilty.”
Morgan
“Either Noah or Hayden is guilty.”
Hayden
“Morgan is guilty.”
Marley
“Kendall is innocent.”
Who is guilty?
Solution: Hayden
If Hayden is guilty, Hayden's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.