According to Andrea da Parma, abbot of San Fedele di Strumi, who wrote a Vita concerning Arialdo, the church in Milan was rife with immoral clerics, fornicating, sleeping with prostitutes, lending money, and selling indulgences.

[2] Together with Bishop of Lucca Anselmo da Baggio (later Pope Alexander II), Arialdo headed the pataria, a movement that sought to reform Milan's simoniacal clergy.

[2] Pope Stephen IX removed the excommunication and Arialdo returned to Milan to continue his efforts towards reformation.

[3] Ten months after the assassination, his body was found in Lago Maggiore (allegedly in a perfect state of preservation, and emitting a sweet odour).

Subsequently, Arialdo's body was interred in the church of St. Celsus, and in the following year, 1067, Pope Alexander II declared him a martyr.