Moved to the prison server forum.
PvP is an offense no matter how many times an Officer or Sergeant sees you do it. Officers can kill for PvP offenses, and Sergeants can jail if requested by an Officer. Using third-person mode is unfair when used to spot PvP happening behind you.
Prison staff cannot use death messages, nor can they go off the sounds. The combat tag plugin was added to resolve any conflicts that may arise as to who hit who. If a player can prove they were hit without hitting anyone else (screenshot and post to forum), action will be taken against the Officer or Sergeant.