Former president Mohamed Morsi went on trial Tuesday on charges of breaking out of prison, a day after Egypt's military endorsed the army chief who deposed him as a presidential candidate.
With tensions linked to the trial running high, gunmen shot dead a police general as he left his home in a west Cairo neighbourhood, the latest in a wave of attacks on security officials.
Morsi, ousted by the army in July, is already on trial for inciting the killings of opposition activists during his presidency and faces two other trials that have yet to begin.
State television showed Morsi, dressed in a white prison uniform, in the dock along with 21 other defendants, among then the supreme guide of his now-banned Muslim Brotherhood, Mohamed Badie.
He is being tried with 130 others, including dozens of members of the Brotherhood, the Islamist Palestinian movement Hamas and Lebanon's Shiite militant group Hezbollah.
The rest of the defendants are being tried in absentia.
The trial is being held under tight security in a makeshift courtroom inside a police academy on the outskirts of Cairo.
Morsi also faces charges of espionage involving Hamas, with that trial due to open on February 16, and for insulting the judiciary, for which a date has yet to be set.
The Islamist leader was deposed following massive popular protests against his one-year rule.
Tuesday's hearing comes a day after the powerful military gave its backing to army chief Field Marshal Abdel Fattah al-Sisi to run for the presidency after he led the ouster of Morsi -- Egypt's first democratically elected president.
The trial is part of a relentless government crackdown on Morsi and his Islamist supporters that has seen 1,400 people killed since he was deposed, according to Amnesty International.
Most of those killed have been pro-Morsi demonstrators in street clashes with police and the former president's opponents.
Top security figure murdered
In the latest bloodletting, police General Mohamed Saeed was leaving his home when gunmen on a motorbike opened fire at him, hitting him in the head and the chest before fleeing, security officials said.
He died in hospital, they added.
Saeed was the head of interior minister Mohamed Ibrahim's "technical department."
Ibrahim himself was targeted by a car bomb in Cairo on September 5, but escaped unhurt.
That attack was claimed by Al-Qaeda-inspired group Ansar Beit al-Maqdis, or Partisans of Jerusalem.
The group has also claimed some of the deadliest bombings carried out across the country following Morsi's ouster.
It said it carried out four bombings targeting police in Cairo on Friday that killed six people, a day before Egyptians marked the third anniversary of the toppling of Hosni Mubarak.
Tuesday's trial date is symbolic as it marks the third anniversary of the prison break.
Prosecutors have said almost 70 of the defendants belonged to Hamas or Hezbollah and that some of them were also accused of murdering police officers and helping thousands to escape during the jailbreak.
Morsi was among those who escaped from Wadi Natrun jail.
Sisi, the man who deposed him, is expected to run for the vacant presidency after receiving the backing of the military Monday.
Wildly popular for overthrowing Morsi, he is now expected to resign as army chief and put himself forward as a candidate in the election scheduled to be held by mid-April.
A victory for the 59-year-old Sisi would continue a tradition of Egyptian presidents drawn from the armed forces.
To his supporters, Sisi is the best option for ending three years of instability following the 2011 uprising that ended the presidency of Hosni Mubarak, another former military officer.
On Saturday, thousands poured into Cairo's Tahrir Square to back Sisi's candidacy, after he said he required "public demand" to stand in the election.