Case 207
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.
Frankie
“Alex and Kendall are both innocent.”
Marley
“Cameron is guilty.”
Alex
“Cameron is innocent.”
Kendall
“Frankie and Alex are both innocent.”
Cameron
“Frankie is innocent.”
Who is guilty?
Solution: Marley
If Marley is guilty, Marley's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.