Isotta convinced Sigismondo to name him heir to Sigismondo's lordship, a choice also supported by Pope Paul II.
At Sigismondo's death in 1468, Isotta and Sallustio took control of his territory.[4]Roberto Malatesta, an illegitimate son of Sigismondo, opposed his father's decisions. He would take control of Rimini with assistance from Milan, Florence, and Naples.[5] In 1470, he would have Sallustio assassinated.[5][6][1] Roberto would do the same to another of Sigismondo's sons, Valerio Galeotto Malatesta [it], in November of the same year.
^D'Epiro, Peter; Pinkowish, Mary Desmond (2001). "Twenty-two: Sigismondo Malatesta: The condottiere with a vision". Sprezzatura: 50 Ways Italian Genius Shaped the World. New York: Anchor Books. p. 159. ISBN0-385-72019-X.