Since the July 3 military ouster of President Mohamed Morsi, a leader of the Muslim Brotherhood and Egypt's first freely elected president, the Arab world's most populous nation has been in turmoil amid massive protests by pro-Morsi Islamists.
More than 800 people have been killed in recent weeks, most of them protesters slain by police gunfire in a heavy-handed crackdown by the regime. One was a son of Brotherhood leader Mohamed Badie, gunned down with 95 other people in an afternoon of clashes Aug. 16.
Badie and 50 other Brotherhood figures have been arrested and thrown in prisons where Mubarak incarcerated tens of thousands of Islamists during his 30-year-rule.
The Brotherhood, formed in 1928 and the godfather of all the radical Islamist groups across the Muslim world, has won all five elections held since Mubarak was deposed Feb. 11, 2011.
The regime is also grappling with a worsening jihadist insurgency in the vast Sinai Peninsula that last week triggered a major offensive by the army with tanks and airstrikes.
Authorities have blamed the Brotherhood for a series of bomb attacks and plots, including a Sept. 5 attempt to assassinate Interior Minister Mohamed Ibrahim near his Cairo home.
Ibrahim, a key figure in the security apparatus, announced in July several controversial police units, nominally disbanded after Mubarak's ouster, were being restored to help counter the widening Islamist-led unrest.
At the same time, interim Prime Minister Hazem el-Beblawi was given the power to impose a state of emergency, a pillar of Mubarak's rule. He proposed disbanding the Muslim Brotherhood, raising the stakes in what has become a bloody struggle between the state and the Islamists for control of the country.
The restored police units include the State Security Investigations Service, or Mabhith Amn al-Dawla, the most notorious of Mubarak's hated police apparatus and a symbol of repression.
Several other units that specialized in hunting down Islamists, -- outlawed from the 1950s during the rule of Gamal Abdel Nasser until Mubarak's fall -- and all those who opposed the state, were also reconstituted.
In March 2011, all these organizations were replaced with a new National Security Service, which was supposed to be transparent and accountable.
Perhaps ominously, Ibrahim referred to the NSS by its Mubarak-era name.
"These units committed the most atrocious human rights violations," said Aida Seif al-Dawla, a leading human rights activist and the head of a group that aids victims of state brutality. "Incommunicado detentions, killings outside the law. These were the units that managed the killing of Islamists during the 1990s. It's an ugly authority that has never been brought to justice."
Liberals are increasingly alarmed at the way the military regime, headed by army chief of staff Gen. Ahmed-Fattah al-Sisi, now characterizes the security operations as aimed at "fighting terrorists" rather than political activists.
That catch-all strategy has heightened concerns about the return of the brutal security state that existed under Mubarak, who ruled for 30 years before he was driven from power in the Arab Spring uprising of 2011.
There are suspicions that the "Deep State" -- secretive, illegal groups within the state apparatus -- are behind many recent violent incidents, seeking to stoke up public anger against the Islamists and those who question the state.
The resurrected Mabhith Amn al-Dawla is frequently mentioned in this regard.
The Aug. 17 release of Mubarak, who'd been imprisoned since his downfall, convinced many Egyptians that the democratic objectives of the 2011 revolution have been shredded in the turmoil that has gripped the country since that uprising.
It was, after all, the same military that forced Mubarak to step down in 2011.
Al-Sisi, hailed by many Egyptians as their savior from Islamist tyranny, insists he doesn't want to be president.
International affairs commentator David Gardner, an old Middle East hand, cautioned, "The army, the country's paramount institution ... is clearly determined to secure its power, privileges and prestige in the country's political and economic affairs -- just as it did, not just under Mubarak but with Morsi."