Case 248
The Vanished Key
A locked evidence cabinet was opened without permission.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Harper
“Reese is innocent.”
Cameron
“Reese and Marley are both innocent.”
Reese
“Harper and Cameron are both innocent.”
Blake
“Reese is guilty.”
Marley
“Either Harper or Blake is guilty.”
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.