Franzone was a servant to Giovanni Andrea Lampugnani, the head conspirator in a plot to assassinate the Milanese Duke.
After a brief exchange of words, Lampugnani rose suddenly, stabbing the Duke in the groin and chest.
As the Duke bled to death in the church, one witness claims that Franzone plunged his hands directly into the flowing blood.
In the pandemonium that immediately ensued, Franzone made his escape, as did all the other assassins except Lampugnani, who was killed.
The bodies of the three men were torn from groin to neck and affixed to the gates of Milan as a warning to others; the heads were separated and displayed on lances on the city's belltower.