An Egyptian court on Thursday acquitted a police officer of charges of torturing an ultraconservative Muslim to death, the third defendant to be found not guilty in the case, a judicial source and a lawyer have said.

Mohamed Al-Shemy of the notorious State Security investigations department was sentenced in June 2012 to 15 years for using torture to extract confessions from Sayed Belal, a Salafist whom police accused of involvement in a 2011 suicide bombing at a Coptic Christian church in the port city of Alexandria.

The court on Thursday acquitted Al-Shemy, who successfully appealed his sentence and was granted a retrial in May 2014, defence lawyer Mustafa Ramadan told Ahram Online

Four other police officers of the now disbanded department were handed down life in jail terms in absentia in June 2012, two of whom have been released, while one is still on the run.

The charges against the defendants included "murder, unlawful detention, torture to extract confessions and indecent assault," the lawyer said.

Belal was one of 7 victims in the case.

The court on Thursday also ordered the release of the fourth defendant in the case, Osama Al-Konaies, for spending well over the maximum detention period in —18 months in this case, the lawyer added.

According to Egyptian law, those sentenced in absentia automatically receive retrials when they turn themselves in.

Belal was arrested along with other suspects on the back of a bombing on 1 January, 2011, when at least 21 worshippers marking the New Year were killed while leaving a church in Alexandria.

Police brutality was among the main grievances that galvanised public anger and led to the popular revolt that ousted long-time autocrat Hosni Mubarak in early 2011.

The death of Khaled Said, also from Alexandria, who was tortured to death by two police officers in June 2010 became a rallying call for the uprising.

But the security forces have regained their image in the eyes of many of the masses, following the ouster of Islamist president Mohamed Morsi after a single year in office and a deadly crackdown on his supporters.

In April, a court sentenced a police colonel for three years and 13 policemen to one year in prison for torturing two prisoners to death in 2006.