Case 232
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.
Jules
“Either Dakota or Lane is guilty.”
Dakota
“Casey and Avery are both innocent.”
Casey
“Either Jules or Dakota is guilty.”
Avery
“Dakota is innocent.”
Lane
“Either Jules or Avery is guilty.”
Who is guilty?
Solution: Jules
If Jules is guilty, Jules's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.