But the answers could complicate the new president's efforts to stabilize Egypt and deal with its economic woes since they might bring pressure to go after still powerful figures in the security forces.
Mubarak and former Interior Minister Habib el-Adly were sentenced to life in prison in June for failing to prevent the killings during the 18-day revolution in 2011 that toppled the leader's 29-year regime. Standing trial with them were six police generals, five who faced the same charges, while the sixth was accused of gross negligence. All six were acquitted.
The ruling raised widespread public anger over what was seen as a shoddy prosecution case. Many believed Mubarak should have been convicted for directly ordering the lethal crackdown.
The presiding judge of that first trial said the prosecution's case lacked concrete evidence and failed to prove the protesters were killed by the police, indirectly giving credence to the testimony of top Mubarak-era officials that "foreigners" were behind the slayings between Jan. 25 and Feb. 1, 2011.
Nearly 100 police officers have been brought to trial in a string of cases over the nearly two years since Mubarak's Feb. 11, 2011, ouster. All were acquitted or received suspended sentences on charges of killing and wounding protesters, a trend that has angered those behind the uprising who say authoritarian rule cannot truly be ended without dismantling what is left of the Mubarak regime, particularly in the large police force and pervasive security agencies.
On Sunday, Egypt's main appeals court overturned the life sentences against Mubarak and el-Adly and ordered a new trial for the two. It also granted the prosecution's request to overturn the acquittals of Mubarak, his two sons and an associate of the former president, Hussein Salem, on corruption charges. Salem was tried in absentia and remains at large. Six police generals who were found not guilty also will be tried again.
No date has been set for the new trial and no word on whether they would be all be tried together or separately.
Mubarak's supporters cheered the decision, which came in response to an appeal by the former leader's lawyers.
But the outcome of the new trial could bring a new setback for the 84-year-old ousted leader.
If convicted again, the life sentence passed against Mubarak and el-Adly would be upheld. They could also have their sentence reduced or even be acquitted.
This time, the case could be boosted by new evidence contained in a confidential report by a fact-finding mission appointed by Mubarak's successor, Islamist President Mohammed Morsi.
Ahmed Ragheb, a prominent rights lawyers and a member of the fact-finding mission, said the report has established the use of deadly firearms by the police against the protesters.
That finding, if substantiated in the proceedings, would bring responsibility for the crackdown closer to Mubarak and el-Adly.
The report has also found that Mubarak, contrary to what his defense lawyers have said all along, was fully aware of the extent of the uprising and how security forces dealt with it though a live television feed into his palace.
"This will be a totally new and unrestricted trial in which any new evidence or witness testimony will be admitted, including the report by the fact-finding mission," Ragheb told The Associated Press.
While Mubarak and el-Adly are not likely to draw a heavier sentence, like the death penalty, the retrial could lead to the conviction of the six generals, whose acquittal was a surprise given the key positions they held at the time of the uprising. The six include the commander of the riot police, the security chiefs of Cairo and its twin province of Giza, the head of general security and the director of the feared state security agency.
Protesters calling for Mubarak's ouster clashed with security forces in the early days of the uprising, with police using tear gas, water cannons and clubs to try to disperse the crowds, which swelled to hundreds of thousands in Cairo and cities across the nation of some 85 million people.
The worst day of violence was on Jan. 28, with hours of deadly clashes with police. Video footages from that day showed police trucks running over demonstrators and policemen using what look like firearms against the unarmed protesters. By the end of the fighting, police were broken and withdrew from the streets for most of the rest of the uprising - and they have only partially returned.
The days that followed saw violence whose source was murkier - though protesters blame security forces or Mubarak supporters.
Snipers shot protesters from rooftops or rained rocks and firebombs on them. Men armed with swords and whips and on the back of camels and horses waded into the crowds at Cairo's central Tahrir Square, the epicenter of the uprising. There were also attacks on police stations and jails, freeing thousands of convicts who fueled a dramatic surge in violent crime across Egypt.
But revealing the truth could also bring troubles for Morsi, of the Muslim Brotherhood. It could increase pressure on him to go after suspects in the security agencies, whose goodwill he now needs to cement his government's shaky hold.
Some in the Interior Ministry, which runs the police, have already seemed the resist the rule of the Brotherhood, which is the backbone of Morsi's presidency. During Mubarak's rule, the Brotherhood was the regime's top nemesis and security agencies frequently targeted it in crackdowns.
Recently, Brotherhood officials have criticized police for failing to protect offices of the group that were attacked by protesters during unrest in November and December over the new constitution. The criticism may have been one reason behind the replacement of the interior minister in a Cabinet reshuffle this month.
But moving to prosecute police officers could bring a backlash from security officials Morsi needs right now.
Morsi's tenure has been defined by an enduring lack of security, with police still not fully acting against crime. At the same time, Morsi, who won election in June by a narrow 51 percent of the vote, faces sharp pushback from a liberal and secular opposition that accuses he and the Islamists are recreating the Mubarak dictatorship with a religious slant.
Morsi's troubles are likely to grow when he introduces unpopular economic measures to prop up the country's faltering finances, including reducing huge state subsidies on fuel and hiking taxes and prices to secure a $4.8 billion IMF loan.
Legal expert Nasser Amin said the new trial would proceed in a much less charged atmosphere than the first one, when Mubarak loyalists and relatives of the killed protesters often clashed outside the courthouse.
Attention may be more distracted by campaigning for important parliamentary elections expected to be held in April.
"These elections constitute the only hope to achieve a balance between the country's political forces," said Amin, alluding to the domination by the Islamists of the first parliamentary elections held in late 2011 and early 2012.
"It will be a very intense fight."
(Copyright 2013 by The Associated Press. All Rights Reserved.)