Case 028
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.
Avery
“Frankie is innocent.”
Frankie
“Neither Avery nor Elliot is guilty.”
Riley
“Frankie and Elliot are both innocent.”
Reese
“Elliot is guilty.”
Elliot
“Reese is guilty.”
Who is guilty?
Solution: Reese
If Reese is guilty, Reese's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.