Premise: Francesco Pacelli (February 1, 1872 – April 22, 1935) was an Italian lawyer and the elder brother of Eugenio Pacelli, who would later become Pope Pius XII. He acted as a legal advisor to Pope Pius XI; in this capacity, he assisted Cardinal Secretary of State Pietro Gasparri in the negotiation of the Lateran Treaty, which established the independence of Vatican City.
Hypothesis: Franceso Pacelli brother is a pope