Warden's Confession
That confession would never stand-up in court. Obviously it was made under duress!
shareTrue, but there's bound to be other evidence if an investigation occurs. The confession is grounds to investigate further.
Also ... keep in mind that "under duress" really only applies if you're being questioned by the cops. Evidence that's inadmissable if gathered illegally by the police is often admissable if a private citizen gathers it.