Case 139
The Lost Access Card
A master access card was taken from the reception desk.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Logan
“Dakota is innocent.”
Elliot
“Logan is innocent.”
Dakota
“Either Logan or Rowan is guilty.”
Rowan
“Elliot is guilty.”
Alex
“Neither Logan nor Elliot is guilty.”
Who is guilty?
Solution: Rowan
If Rowan is guilty, Rowan's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.