Case 191
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
“Either Jordan or Riley is guilty.”
Jordan
“Hayden is guilty.”
Riley
“Either Hayden or Jordan is guilty.”
Sam
“Neither Jordan nor Quinn is guilty.”
Quinn
“Riley is innocent.”
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.