Answer
Alfonso of Aragon was the second husband of Lucrezia Borgia. He was a son of Ferdinand II of Aragon and Isabella I of Castile. Alfonso was murdered in 1497 by his brother-in-law, Cesare Borgia, who was also Lucrezia's brother. Cesare was suspected of being involved in the murder of his other brother-in-law, Giovanni Sforza, in 1497.