Case 101
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.
Hayden
“Cameron is innocent.”
Frankie
“Either Jules or Reese is guilty.”
Jules
“Hayden and Reese are both innocent.”
Reese
“Hayden is innocent.”
Cameron
“Jules 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.