The death toll of Al-Warraq's Al-Adra church attack has increased to five, security officials told Al-Ahram's Arabic website.
Officials say Mohamed Ibrahim Ali died on Thursday from a gunshot wound to the head and foot. Another 17 remain injured from Sunday's attack.
Ali was admitted to intensive care after unknown assailants opened fire late on Sunday at a wedding ceremony in the working-class Giza district of Al-Warraq. Four others were killed in the attack, including an 8-year-old girl.
Ali is the first Muslim casualty from Sunday's shooting, which appears to have targeted Christians.
Also on Thursday, Al-Warraq's prosecution proceeded with an investigatory hearing on the police conscripts responsible for guarding the church.
The investigation has revealed that security forces stopped protecting the church in mid-August due to a lack of weapons, the prosecution said.