Case 148
The Swapped Envelope
A sealed envelope was replaced with an empty one.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Parker
“Sam is innocent.”
Sam
“Either Jordan or Kai is guilty.”
Jordan
“Parker is innocent.”
Kai
“Parker is guilty.”
Logan
“Parker and Jordan are both innocent.”
Who is guilty?
Solution: Kai
If Kai is guilty, Kai's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.