Rather than accepting this judgment, Guido countered by organizing a resistance against the pataria.
Then, during the feast of the Ascension, Arialdo upped the stakes by imposing an interdict—an ecclesiastical censure that excludes a person or district from participation in most sacraments, as well as from Christian burial.
Arialdo’s timing and sense of politics appear not to have been quite as well developed as his moral principles and abstract intellect. A riot ensued, and Arialdo was seriously injured in it. (It was not the first time Arialdo had been in physical danger. Earlier, an attempt had been made on his life with a poisoned sword.)
Arialdo withdrew to the safer environment of Pavia. He then began a trip to Rome. Along the way, he was ambushed by men sent by Guido
He did not fare as well as Landolfo Cotta had before him. On June 26 or 27th, 1066, he was taken to an island on Lake Maggiore, where a pair of priests began to torture him. They mutilated his right hand, feet, and genitals, gouged out his eyes, and cut off his ears, tongue, and nose and stuffed them down his throat, before finally killing him and dumping his weighted body into the lake.
Ten months later, on May 3, 1067, Erlembaldo Cotta found Arialdo’s body. According to the story, it was in a state of perfect preservation, and “emitting a sweet smell.” Erlembaldo had the body carried with great ceremony back to Milan, where it was put on display from Ascension through Pentecost, a period of about a week and a half in mid to late spring.
Arialdo was then buried in the church of Santa Maria Pressa San Celso, which had long been associated with holy relics, and was later to be called the “Church of the Miracles." That same year, Pope Alexander pronounced Arialdo a martyr, and canonized him.