Case 346
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.
Riley
“Neither Alex nor Reese is guilty.”
Alex
“Either Frankie or Peyton is guilty.”
Frankie
“Alex is guilty.”
Reese
“Alex and Peyton are both innocent.”
Peyton
“Alex is innocent.”
Who is guilty?
Solution: Frankie
If Frankie is guilty, Frankie's statement is false and every other statement is true. Testing the other suspects creates at least one contradiction.