Opposition politician Abul-Ela Mady was released Wednesday after nearly two years of pretrial detention, Mady's son Ahmed said, two days after a court ordered him set free.
Mady was a supporter of ousted President Mohamed Morsi, who was removed from power by the army following mass protests against his rule in 2013.
Mady was detained on charges related to violence during protests between supporters and opponents of Morsi and his Muslim Brotherhood in July 2013.
The leader of the Muslim Brotherhood, Mohamed Badie, his deputy, Khairat el-Shater, and other Brotherhood leaders are also defendants in the case, judicial sources said.
Mady's release does not mean the case against him has been closed, Ahmed Mady, who is a lawyer, told Reuters.
Egyptian law limits pretrial detention to two years, and a court on Monday ordered that he be released.
Mady, 57, was a member of the Muslim Brotherhood until leaving in the 1990s, hoping to establish a more liberal-leaning Islamist party.
He founded the Wasat, or Center, Party after the 2011 popular uprising that unseated longtime autocrat Hosni Mubarak, who had prevented the formation of the party.