On the 3rd October 1226 Giovanni di Pietro di Bernardone, better known as Francis of Assisi and then simply St Francis, died. He was either 45 or 44, as we don't have the precise birthday. We have however unusually good evidence for the date of his death, in the evening of the 3rd October 1226 (though after dark, so according to the liturgical feast, it would be 4 October). The evidence does not come from a death certificate, but on very early Franciscan sources, written by people close in time to Francis, especially Thomas of Celano, his first biographer, who wrote "Vita prima" on commission by Pope Gregory IX, completed only two years after Francesco died. You can find "Vita Prima" on the Internet Archives. Later medieval sources, including Bonaventure, specify that he died late on a Saturday evening, and that he was buried on the Sunday; this is an important cross-check because the 3 October 1226 was indeed a Saturday. There are more than 1000 sources in APE on St Francis and the world-famous church that takes his name, you can dig here!

A Swiss newsreel about the arrival of St Francis' relics to Friburg in 1956, to celebrate the 700th anniversary of the Friburg monastery, and the 730th anniversary of St Francis' death, Schweizerisches Bundesarchiv

