He at once conveyed the information to the Duke of Ferrara in a letter, in which he said that Giovanni Borgia had been called to Rome by the Pope, and having set out from Forli, had died suddenly in Urbino of a flux.

The fact that he had been in Caesar's camp, and that, according to Elisabetta's letter, he had been taken sick in Urbino, lent some probability to the suspicion that he had been poisoned.
It is worthy of note that Caesar, in his letter to the duke, speaks of the deceased as his brother;[75] and Ercole, in offering him his condolences, January 18th, on the death of the cardinal, also called him Caesar's brother.

Are we thereby warranted in concluding that the younger Giovanni Borgia was a son of Alexander VI?
Further, the Ferrarese chronicler Zambotto, speaking of the cardinal's death, uses the expression, "son of Pope Alexander."[76] If this was the case, the number of Alexander's children must be increased, for Ludovico Borgia was also his son.

This Borgia, who succeeded to Giovanni's benefices, was Archbishop of Valencia and subsequently cardinal.

He reported his promotion to the Marchioness Gonzaga in a letter in which he everywhere speaks of the deceased as "his brother," just as Caesar had done.[77] These statements, however, do not refute the hitherto generally accepted opinion regarding the descent of Giovanni Borgia, "the younger," and Zambotta certainly was in error--the word _fratre_, which he uses in his letter means merely "dear cousin," _fratello cugino_.[78] January 14th news reached the Vatican that Caesar had taken the castle of Forli.