Alexandria's criminal court ordered on Monday the release of Mohamed El-Sheimy, a police officer accused of torturing Sayed Belal to death during investigations into a bomb attack at the Two Saints Church in the Mediterranean city in 2011.
El-Sheimy's release comes after he completed the maximum time for provisional detention.
The decision on Monday follows a ruling by Cairo's cassation court, which approved an appeal filed by the defendant challenging last year's court verdict sentencing El-Sheimy to 15 years in prison. The court also ordered his retrial.
Other defendants in the case over Belal's death have also received long sentences, including Hossam El-Shennawy, Osama El-Keneisy and Ahmed Mostafa Kamel. Defendant Mahmoud Abdel-Alim was deemed innocent after being given a retrial.
The murder took place after Belal, a young Salafist, was arrested on 4 January 2011 during investigations by the now-dissolved State Security Investigations Service (SSIS) into the New Year's Eve bombing of the Two Saints Church in Alexandria.
Signs of torture were found on the victim's body, prompting his family to file a lawsuit against the state security officers.
Twenty-three people died in the attack on the church on 1 January 2011.