Judge Moataz Khafagy first passed the sentence against the men in June and referred the case to the country's highest Sunni Muslim authority for approval, which is required before any execution can be carried out.
The men were charged in connection with violence that erupted when police stormed the town of Kerdasa near Cairo in September and arrested dozens of supporters of ousted President Mohamed Mursi.
Major-General Nabil Farag was shot dead when security forces exchanged fire with militants.
A month earlier security forces had crushed two pro-Mursi protest camps in Cairo. Then-army chief Abdel Fattah al-Sisi launched his crackdown on Islamists after ousting Mursi last year following mass protests against his rule.
Sisi, who took office as president in June, said the Brotherhood would cease to exist in his presidency.