What group was XXX a member of?
Bernard Gui
Bernard Gui (French: (ɡi); 1261 or 1262 -- 30 December 1331), born Bernard Guidoni, also known as Bernardo Gui or Bernardus Guidonis, was a French inquisitor of the Dominican Order in the Late Middle Ages during the Medieval Inquisition, Bishop of Lodève, and one of the most prolific writers of the Middle Ages.
Dominican Order