Demjanjuk testified during the trial that he was imprisoned in a camp in Chełm until 1944, when he was transferred to another camp in Austria, where he remained until he joined an anti-Soviet Ukrainian army group. Demjanjuk had not mentioned Chelm in his initial depositions in the United States, first referring to Chelm during his denaturalization trial in 1981. As Chelm was Demjanjuk's alibi, he was questioned about this omission during the trial by both the prosecutors and the judges; Demjanjuk blamed the trauma of his POW experience and said he had simply forgotten. Demjanjuk also denied having known how to drive a truck in 1943, despite having stated this on his application for refugee assistance in 1948; Demjanjuk alleged that he had not filled out the form himself and the clerk must have misunderstood him. Demjanjuk's denial related both to the supposed operation of a truck's diesel engine by "Ivan the Terrible" for the gas chamber at Treblinka and to the SS's singling out of Ukrainians with experience driving trucks as Trawniki men. Demjanjuk also changed his testimony as to why he had listed Sobibor as his place of domicile from his earlier trials: he now claimed to have been advised to do so by an official of the United Nations Relief Administration to list a place in Poland or Czechoslovakia in order to avoid repatriation to the Soviet Union, after which another Soviet refugee waiting with him suggested Demjanjuk list Sobibor. Demjanjuk also said, "Your Honors, if I had really been in that terrible place, would I have been stupid enough to say so?"