Case 129
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.
Parker
“Logan is guilty.”
Logan
“Drew is innocent.”
Harper
“Either Parker or Logan is guilty.”
Taylor
“Either Parker or Harper is guilty.”
Drew
“Logan is innocent.”
Who is guilty?
Solution: Parker
If Parker is guilty, Parker's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.