In this capacity Gui travelled the region, meeting with local clergy and officials, publicly preaching about the danger of heretical teachings, and inviting those guilty of heretical sins to voluntarily confess in exchange for light penance. He then interrogated those who had been accused of heretical activity by penitents but failed to come forward voluntarily, with the secular authorities enlisted to apprehend and, if necessary, torture the accused. (A papal bull of 1252 permitted torture in cases in which there were "enough partial proofs to indicate that a full proof—a confession—was likely, and no other full proofs were available", although "a confession made after or under torture had to be freely repeated the next day without torture or it would have been considered invalid".)