"Don Pietro de´ Medici (3 June 1554 – 25 April 1604) was the youngest son of Cosimo I de´ Medici, Grand Duke of Tuscany and Eleonora di Toledo.
Early in 1571 he went to Rome and in the spring of 1575 he went to Venice. In 1571 he married his first cousin Eleonora di Garzia di Toledo, whom he accused of adultery and strangled with a dog leash in July 1576 at the Villa Medici at Cafaggiolo. He also had her supposed lover Bernardino Antinori imprisoned and killed.
Eleonora di Garzia di Toledo 1571At the end of 1577, he went for the first of many stays at the Spanish court. He remained in Spain until the end of 1578. During this visit he gained a reputation as a spendthrift and a rake. He left Tuscany in October 1579 to bring Italian troops to Spain and lead them during the mission to Portugal. He stayed in Lisbon until the end of 1582 when he returned to Spain where his presence is documented in 1583 and 1584." - (en.wikipedia.org 13.12.2020)