The Procurator of Justice was the head of the Imperial criminal justice system, charged with prosecuting political prisoners and administering sentences on entire worlds. One individual who served as Procurator was Hethrir, one of Darth Vader's greatest students.
After the Declaration of a New Order, the Procurator declared twenty-seven worlds as expendable, including New Plympto, allowing their exploitation.
Due to the dangerous nature of the office, the Procurator of Justice was normally anonymous. It was only after the Emperor's death at the Battle of Endor that the identity of the Procurator was made public.