Case 053
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.
Casey
“Jordan is innocent.”
Jordan
“Rowan is innocent.”
Avery
“Either Casey or Emery is guilty.”
Rowan
“Neither Casey nor Jordan is guilty.”
Emery
“Either Jordan or Rowan is guilty.”
Who is guilty?
Solution: Emery
If Emery is guilty, Emery's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.