Clashes erupted outside Alexandria Criminal Court on Tuesday as the retrial resumed of two policemen accused of killing Khaled Said.
Protesters chanted against the interior minister and fought with the security forces.
Five men remain in detention after being arrested outside the court. Mahinour El-Masry, a lawyer and member of the Revolutionary Socialists, was also arrested but has since been released, she told Ahram Online.
The brutal murder of Khaled Said, 28, in Alexandria in summer 2010 is considered one of the sparks of the January 25 Revolution.
The retrial, which began on 1 June, has been adjourned until 2 December.
The two defendants, Mahmoud Salah Mahmoud and Awad Ismail Soliman, filed an appeal against their convictions in December 2012, arguing that particular witnesses in the original trial were "dealt with lightly."
On 1 June, the court ordered the defendants' release because they had been detained for 35 months, exceeding the detention cap of 18 months.
In October 2012, the policemen were given seven-year jail sentences for the illegal imprisonment and torture of Said.
Family and supporters of Said were shocked at what they considered a light sentence.