Case 290
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.
Emery
“Either Lane or Blake is guilty.”
Lane
“Neither Emery nor Jordan is guilty.”
Blake
“Either Lane or Jordan is guilty.”
Jordan
“Neither Emery nor Kendall is guilty.”
Kendall
“Emery is innocent.”
Who is guilty?
Solution: Blake
If Blake is guilty, Blake's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.