The retrial of former Egyptian president Hosni Mubarak along with his former interior minister has begun at a court in the capital Cairo.
Mubarak, Habib al-Adly and ex-security chiefs are accused of complicity in the murder of protesters during the uprising that unseated him in 2011.
Television footage showed Mubarak, dressed in white and wearing sunglasses, wheeled out of an ambulance on a stretcher on Saturday and taken into Cairo's Police Academy where the trial is being held.
He was flown by helicopter to the courthouse, according to the Reuters news agency.
Al Jazeera's Anita McNaught, reporting from Cairo, said Mubarak is required by law to attend the proceedings "because at the the last trial he attended the session from beginning to end".
"He'll be back inside the cage, along with his two sons, his former interior minister, Habib al-Adly, and the six [security] officials. That's what the Egyptian law requires," said our correspondent.
She said that although Egyptians had turned out to witness the proceedings, "many feel the country has more important things to worry about".
Egypt's highest appeals court ordered a retrial in January after accepting appeals from both the defence and the prosecution.
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Each cited different shortcomings with the trial, which ended with life prison terms for Mubarak and his interior minister but was criticised for the weak evidence offered by the prosecution.
Mubarak, al-Adly and four senior aides are charged with involvement in the killing of more than 800 protesters who died in the 18-day uprising. Mubarak's two sons, Gamal and Alaa, face retrial on charges of financial corruption.
Mubarak's imprisonment last June was a historic moment; he was the first ruler toppled by the Arab Spring uprisings to stand trial in person.
But the case exposed the difficulties of attaining justice in a country whose judiciary and security forces are still largely controlled by figures appointed during his era.
Six senior interior ministry officers - two of them charged with lesser crimes - were acquitted. The prosecution complained that the ministry had failed to co-operate in providing evidence.
The judge convicted Mubarak and Adly on the grounds of their failure to stop the killing, rather than actually ordering it.
Change in charge
Mina Khalil, a law professor at the American University in Cairo, told Al Jazeera that there was a change in the charge against Mubarak.
"It seems that the court in its first decision has changed the crime that he was initially charged with. Initially it was killing the protesters ... now it's a crime of omission, not having done anything in order to prevent protesters from being killed," he said,
This time, the prosecution is expected to draw on the findings of a fact-finding committee established by president Mohammed Morsi last year.
Britain's Guardian newspaper published this week what it said were leaks from the report, alleging the military had been involved in torture, killings and forced disappearances during the uprising.
Ali Hassan, a member of the inquiry panel whose son was killed in the uprising, said the report should condemn Mubarak and the interior ministry officials. "The minimum punishment for them should be death," he said.
But the former president cannot face the death penalty. Under Egyptian law, he cannot receive a harsher sentence than he did during his original trial.
Mubarak was sent to Tora prison after being convicted last year and subsequently moved to a military hospital. He appeared at court hearings on a hospital bed, alongside his two sons.
While the sons were cleared of the charges in that trial, they remain in jail pending other corruption investigations. The retrial will also include a charge against Mubarak of improperly facilitating a natural gas deal with Israel.