 He was released on a technicality in 1982, re-tried, and again sentenced to life imprisonment on 4 October 1985.Due to his advanced age and poor health, the sentence was not imposed and he was released.Sobibor survivor Thomas Blatt was among those called to testify as a witness against Frenzel at the post-war trial, and when Blatt traveled to the court venue city, Blatt and Frenzel met at a hotel in order to discuss historical questions and technical details about camp operation for the history of the uprising Blatt was then writing; the event is presumed to be the only time that a Nazi death camp supervisor was interviewed by a death camp prisoner.