(CNN) -- A medically-equipped helicopter ferried former Egyptian President Hosni Mubarak to court Saturday, where 3,000 security personnel were gathered to maintain peace, state TV reported.
At least 25 armored vehicles secured the court venue.
The former autocratic leader faces retrial in the killings of hundreds of civilian protesters who took to the streets for two weeks in early 2011 to demand his removal from office after three decades of rule.
Hundreds more civilians went missing during the revolution and remain unaccounted for.
Past court appearances have stirred protests against him as well as impassioned supporters outside Cairo's police academy, where the trial is being held. Both sides have clashed violently in the past.
Mubarak appeared on the first day of the retrial with other defendants in a cage, where defendants are customarily seated for trial in Egypt. He lay on a stretcher but appeared alert and wore dark sunglasses. Family members of those killed gathered outside the police academy and remained calm.
Saturday's appearance follows a previous attempt at a retrial in April, which ended abruptly when a judge recused himself and walked out of the courtroom amid jeers from angry onlookers.
Some of them were relatives of protesters who were killed during the Egyptian revolution.
The former strongman, who stepped down on February 11, 2011, and his former interior minister, Habib al-Adly, were found guilty and sentenced to life in prison last year on charges that they were complicit in the protesters' killings.
Mubarak's sons, his interior minister and six of his security aides also face trial.
The defendants were granted a retrial after appealing their convictions.
The six security aides last year were acquitted of charges related to the killings, and Mubarak's two sons -- Gamal and Alaa -- were acquitted of corruption charges. But they, too, were ordered to be retried after President Mohamed Morsy ordered a new investigation last year.
A public prosecutor has sent Mubarak -- who spent months detained in a military hospital -- back to prison last month, prosecutor spokesman Mahmoud Hefnawi told the state-run al-Ahram newspaper.
Mubarak's health has been a bone of contention during his trial and incarceration. He suffered a heart attack after relinquishing power and had maintained that he was physically unfit to stand trial.
Hefnawi said the prosecutor reviewed a report of Mubarak's health and determined that he is fit to return to prison, the newspaper reported.
Mubarak has been held since his guilty verdict last year.
He is also charged with seizing public funds and misusing political influence. He also faces a corruption charge that was not part of the original trial. Mubarak is accused of selling natural gas to neighboring Israel for prices below fair market value.
Mubarak and the other defendants plead not guilty Saturday to all charges. Court was adjourned until June 8.
CNN's Basil Yousuf contributed to this report.