 While in prison, he secretly began to say Mass and wrote letters, reflections on Advent, on Christmas, and other spiritual subjects, which were smuggled out of the prison before his trial.On 8 December 1944, Delp had a visit from Franz von Tattenbach SJ, sent by Rösch to receive his final vows to the Jesuit Order.This was supposedly forbidden, but the attending policemen did not understand what was going on.