When the Duke's procession arrived at Mass, Lampugnani and the two other assassins (Gerolamo Olgiati and Carlo Visconti) stepped before the Duke, Lampugnani going down on one knee. After a brief exchange of words, Lampugnani rose suddenly, stabbing the Duke in the groin and chest.
When the Duke's entourage arrived at Mass, Lampugnani and the two other conspirators (Gerolamo Olgiati and Carlo Visconti) stepped forward, with Lampugnani kneeling down. Following a brief conversation, Lampugnani swiftly rose, striking the Duke in the groin and chest.