He was born to Francesco Sforza, a popular condottiero and ally of Cosimo de' Medici who would gain the Duchy of Milan in 1450, and Bianca Maria Visconti.

The false identity was necessary as he had to pass by the territories of the family's enemy, the Duke of Savoy, who made an unsuccessful attempt on Sforza's life.

There were three principal assassins involved in Sforza's death: Carlo Visconti, Gerolamo Olgiati, and Giovanni Andrea Lampugnani, all fairly high-ranking officials at the Milanese court.

His motives were based primarily on a land dispute, in which Sforza had failed to intervene in a matter which saw the Lampugnani family lose considerable properties.

Evidence from the conspirators' confessions indicated that the assassins had been encouraged by the humanist Cola Montano,[6] who had left Milan some months before, and who bore malice against the duke for a public whipping some years before.

While being tortured, Olgiati also uttered the famous words, "Mors acerba, fama perpetua, stabit vetus memoria facti" (Death is bitter, but glory is eternal, the memory of my deed will endure).

[7] Similar elements indicate that this assassination was likely influential in the Pazzi conspiracy, a subsequent attempt to dethrone the Medici family in Florence and to replace them with Girolamo Riario.