The bull was issued in the wake of the murder of the papal inquisitor of Lombardy, St. Peter of Verona, who was killed by a conspiracy of Cathar sympathizers on 6 April 1252.
Their castle stood in the Thuringian Forest on the Border of Hesse and they had embraced Albigensian (i.e., Cathar) doctrines, combining Gnostic and Christian beliefs.
He was a close friend to inquisitor Pietro da Verona and actively collaborated with the Inquisition in prosecuting heretics, especially the believers of the Church of Concorezzo, a very active Cathar group of that was supported by the bishop of Concorezzo (a town North-East of Milan, near Monza) and by local feudatory Filippo Confalonieri.
Originally a notary from Ax-les-Thermes, he travelled to Lombardy and Piedmont with his brother, Jacques, in the 1290s and converted to Catharism.