CAIRO — Egypt is launching a civilian investigation of the country's former military rulers for their alleged role in the killing of protesters during their 18 months in power, a court official and the state news agency reported Monday. International and local rights groups have pressed Egypt's newly elected president and other authorities to probe the council of military officers who ruled the country from the February 2011 overthrow of Hosni Mubarak to this summer. At least 120 protesters died in clashes with security forces and soldiers during this time. It is unprecedented for civilians to probe officers, normally protected from oversight by anyone outside the military. Rights groups say that this has given the army a sense of impunity. The court official said that an investigative judge, Tharwat Hamad, was assigned to look into accusations against Field Marshal Hussein Tantawi and other members of the Supreme Council of the Armed Forces. The official spoke on condition of anonymity. Lawyers say that Hamad had also presided over the investigation into the killing of 26 Coptic Christian protesters and a soldier in October 2011. It is not clear how far the investigative judge will be able to press the probe, or summon the generals for questioning. SCAF passed a law before giving up power that protects them from civilian investigation even after they are out of service. Lawyers say the investigator might be able to find a legal way around the ban — for example, summoning the generals in their capacity as political leaders at the time — or might refer the case to a military prosecutor. Egyptians have filed over 100 complaints with the country's prosecutors against the military rulers, including Tantawi, his No.2 Lt. Gen. Sami Anan, and other military generals, who were sitting on the military council in charge of running the country since February 2011. The generals handed over power to the country's first elected civilian president at the end of June. But the transitional period was marred by violent clashes with protesters who accused the generals of mismanaging the country, or doubted their intent to step down. Council members did not address accusations of killing protesters, while military officials frequently accused protesters of attacking troops. It was not immediately possible to contact any of the now-retired generals. Newly elected President Mohamed Morsi after taking office quickly moved to cement his authority over the generals, canceling a SCAF decree that granted the military powers that undercut his own. He has promised the protesters' families that he would mete out justice against those responsible for the killings. Weeks after he took office, he retired Tantawi and Anan from active military service, replacing them with a new defense minister. But he also granted the two generals the country's highest honors, raising fears that the generals may evade responsibility for alleged abuse during their rule. In two extensive reports released this month, the London-based Amnesty International urged Morsi to ensure full and impartial investigation into abuses by the military and police during the transition, saying a culture of impunity only allows them to continue. The group said previous investigations by civilian judges have failed to hold to account members of the military forces. Amnesty said the army's response to protests was “disproportionate,” citing cases when live ammunition was fired in response to the lobbing of stones or firebombs. It also cited the October 2011 incident when an army vehicle ran down a crowd of mostly Coptic Christian protesters, killing 15. Another 11 protesters and a soldier died by gunshot. — AP