Egypt's military ruler and Hosni Mubarak's former confidant testified Saturday in a rare high-profile appearance at the trial of the ousted president charged with complicity in the killings of protesters during the crackdown on Egypt's uprising. Mubarak was present in the courtroom during Tantawi's testimony, lying on a gurney inside the defendants' cage. Tantawi, who was defense minister for two decades, could provide critical insight into Mubarak's alleged role in the deaths of nearly 840 protesters as well as insider revelations about the former regime's final days. Also on trial with Mubarak and facing the same charges are his former Interior Minister Habib el-Adly and six senior former security officials. Separately, Mubarak and his two sons, Alaa and Gamal, also face corruption charges. The trial is also seen as a test between Egypt's traditional power structure and the impatience for clear breaks with the past, seven months after Mubarak was toppled in February and power shifted to a military council headed by Tantawi. As Tantawi testified, dozens of activists and families of slain protesters rallied outside the court, chanting, “Tantawi, tell the truth, is Mubarak a killer or not,” as they waved pictures of those killed in the uprising. Addressing a graduation ceremony of police cadets in May, Tantawi said the Supreme Council of the Armed Forces convened in the middle of the uprising and decided not to open fire at the protesters. But he didn't elaborate on who gave the orders for security forces to turn their weapons against protesters.