Case 310
The Missing File
A signed contract file vanished from the archive.
Rule: exactly one suspect is guilty. The guilty suspect lies. Every innocent suspect tells the truth.
Marley
“Riley is innocent.”
Blake
“Neither Marley nor Riley is guilty.”
Taylor
“Neither Marley nor Blake is guilty.”
Emery
“Either Taylor or Riley is guilty.”
Riley
“Either Blake or Emery 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.