Case 287
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.
Lane
“Neither Drew nor Logan is guilty.”
Drew
“Finley is guilty.”
Finley
“Either Lane or Drew is guilty.”
Riley
“Neither Lane nor Logan is guilty.”
Logan
“Lane and Drew are both innocent.”
Who is guilty?
Solution: Finley
If Finley is guilty, Finley's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.