Egypt’s general-prosecution has begun questioning police over the killing of leftist activist Shaimaa El-Sabagh who was shot at a protest in downtown Cairo on Saturday.
Prosecution has also seized three surveillance cameras from Talaat Harb Square where the incident took place.
The Association of Freedom of Thought and Expression said on Sunday that five civilian participants in the protest, who were deatined since Saturday, were first asked by police to give their accounts.
Prosecutors accused them of organising an unauthorised protest, rioting and attacking security forces before releasing them on Monday morning.
Azza Soliman, a lawyer and rights activist, posted her personal testament to police about the circumstances of Shaimaa's death on her Facebook account.
Soliman wrote that she accidentally encountered the protest in Talaat Harb Square in downtown Cairo and saw police quickly firing tear gas and bird shot to disperse it.
Soliman said she went to the police station voluntarily as an eye witness, but she was questioned as an accused person before police released her.
El-Sabagh, 33, was heading, with around two dozen marchers, to Tahrir Square to lay flowers in the memory of those who died during the 25 January 2011 uprising.
Forensic Medicine Authority spokesperson Hesham Abdel-Hameed said El-Sabagh died from a birdshot injury, causing significant damage to her heart and lungs.
The incident sparked fury among activists and sparked condemnation on social media. The interior ministry has denied accusations by marchers that a policeman had gunned El-Sabagh down.
Police said marchers attacked them with fire crackers. However, the Socialist Popular Alliance Party said in a statement that their march was peaceful.
Members of the Socialist Popular Alliance Party, which organised the march, said the march was not authorised by the police but was announced in advance.
El-Sabagh was an advocate for workers' rights and a leading member of the Socialist Popular Alliance Party in Alexandria, a group which supported both the January 25 revolution and the June 30 anti-Brotherhood protests.
She is survived by her five-year-old son and her husband.