Case 030
The Missing Ledger
A confidential ledger disappeared from the office.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Parker
“Hayden is guilty.”
Kai
“Parker and Quinn are both innocent.”
Hayden
“Quinn is guilty.”
Quinn
“Parker and Kai are both innocent.”
Reese
“Neither Kai nor Quinn 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.