Case 205
The Empty Safe
A small office safe was found empty in the morning.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Avery
“Either Finley or Riley is guilty.”
Finley
“Neither Avery nor Quinn is guilty.”
Riley
“Finley is guilty.”
Blake
“Avery is innocent.”
Quinn
“Finley and Blake are both innocent.”
Who is guilty?
Solution: Riley
If Riley is guilty, Riley's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.