Case 243
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.
Logan
“Either Riley or Hayden is guilty.”
Peyton
“Finley and Riley are both innocent.”
Finley
“Hayden is guilty.”
Riley
“Neither Logan nor Peyton is guilty.”
Hayden
“Either Logan or Finley is guilty.”
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.