The secretary-general of the Socialist Popular Alliance Party was released from police custody on Sunday along with six other party members, after being arrested on Saturday for protesting, the group said on Facebook.
Secretary-general Talaat Fahmy, a leading party official, was questioned by prosecutors along with the other arrested members regarding Saturday's protest and its subsequent dispersal by police. A leading member of the party, Shaimaa El-Sabagh, was shot dead during the dispersal.
Police officials have blamed "infiltrators" for her death, while the party has accused the police of the "premeditated murder" of El-Sabagh.
El-Sabagh's funeral was held earlier on Sunday in Alexandria, while Fahmy and the other members were still in custody. They were released without bail.
The party called for the protest on Saturday to commemorate the victims of the 2011 revolution, with a march to lay flowers in Tahrir Square. The march was dispersed in Talaat Harb Square.
A law passed in 2013 criminalises protests that have not been pre-approved by the police.