Case 035
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.
Hayden
“Parker and Alex are both innocent.”
Sam
“Either Parker or Alex is guilty.”
Parker
“Alex and Quinn are both innocent.”
Alex
“Hayden is innocent.”
Quinn
“Either Hayden or Sam is guilty.”
Who is guilty?
Solution: Sam
If Sam is guilty, Sam's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.