ROME—The Vatican is beginning the elaborate sequence of events for mourning, burying and replacing Pope Francis.

On Monday evening, some 12 hours after the pope died, the Vatican’s camerlengo, or chamberlain, ceremonially certified the pontiff’s passing. By tradition, the camerlengo, American Cardinal Kevin Farrell, called out the late pope’s baptismal name, Jorge Mario, three times. On receiving no response, he declared that the Holy See is vacant.