Mubarak's actual worth remains a mystery. A recent claim that he and his sons Gamal and Alaa may have amassed a fortune of up to $70 billion -- greater than that of Microsoft's Bill Gates - helped drive the protests that eventually brought him down.
Corruption was endemic in Mubarak's Egypt where 40 percent of the country's 80 million people live on $2 or less a day, and critics accused officials of usurping the nation's wealth. Egyptians have long complained of an unspoken policy of sweetheart deals that allowed top officials and businessmen to enrich themselves.
In recent days, watchdog groups and private lawyers have demanded that the country's chief prosecutor launch criminal investigations against the Mubaraks and some of their wealthy associates. Scores of former government officials have already been banned from travel and several, among them four former Cabinet ministers, have had their assets frozen.
How far these investigations will go ultimately depends on the political will of Egypt's leadership, said Eric Lewis, a partner with Washington-based law firm Baach, Robinson & Lewis, which specializes in international asset tracing and has done work in Kenya and Pakistan.
"What you often find is that while there's a kind of political impetus that seems to want to do it, the reality is that the real urge for transparency is more symbolic than real," Lewis said.
Far-reaching corruption probes could test the resolve of senior military officials who are running the country in the transition period. Some warn that a purge of Egypt's tycoons could make economic recovery from the political crisis more difficult.
Anti-corruption campaigners are calling for a speedy investigation and are urging countries other than Switzerland to freeze assets pre-emptively. "It's going to be a very difficult task, but in the interest of public money, things need to move now," said Omnia Hussien, Egypt expert at the advocacy group Transparency International.
The Mubaraks have never publicly discussed their assets. Hosni Mubarak's official monthly salary as president, counting benefits, came to 4,750 Egyptian pounds ($808), in 2007 and 2008, according to a Cairo think tank.
Rumors of hidden riches, such as expensive real estate in Britain, the United States and elsewhere, were fueled by the cozy ties between the Mubaraks and Egypt's business elite. The sale of state companies and public land for cheap, starting in the 1990s, were key sources of enrichment for the two sides, said Ahmed Elsayed Elnaggar, editor of Egypt's Economic Report.
"Privatization ... is the biggest corruption process in Egypt all over its history, from the period of the pharaohs, until now," he said.
In the past six months, two leading real estate companies have seen projects challenged in court over such alleged links.
In a case that captivated the country, Talaat Moustafa Group saw its $3 billion planned Madinaty community challenged on claims it was illegally awarded to the firm without the required bidding process, at a loss of $26 billion to the public coffers.
The country's highest administrative court upheld a ruling that the government had to re-offer the land, a decision that threatened to cast doubt on more than 100 other such projects in Egypt. Instead, a government-appointed committee re-awarded the contract, essentially on the same terms, arguing that it was in the national interest to retain the existing ownership and that TMG's work on the land had altered its value.
TMG had been headed by Hisham Talaat Moustafa, a former parliament member who was subsequently stripped of his immunity and sentenced to 15 years for ordering the murder of his Lebanese diva girlfriend.
Palm Hills Development, specializing in upscale residential compounds, faced a similar case - and its ownership structure is a case study of the ties between public officials and the business world. Relatives of the recently fired housing minister and of a transportation minister who resigned in 2009 either hold stakes in or are on the board of one of the major shareholders of Palm Hills.
Mubarak's younger son, 47-year-old Gamal, set himself up as the director of a London-based investment firm called Medinvest Associates Ltd. in 1996, but resigned in 2001. Said Kaba, a current director of Medinvest, said the company is no longer linked to Mubarak's relatives, telling the Sunday Times in London that he knew little about the family's possible U.K. investments.
Medinvest, based in a stone-front building in London's swank Knightsbridge neighborhood, is listed as having one employee and 50,000 pounds sterling (nearly $80,000) of issued capital - the minimum needed to get a trading certificate, operate a business and borrow. The company's profit and turnover weren't disclosed. Its net assets were valued at just over 225,000 pounds (nearly $360,000).
Gamal Mubarak is listed as the owner of 28 Wilton Place, a six-story Georgian townhouse a few blocks from Medinvest's office.
The Cairo-based Mideast investment bank EFG-Hermes said Gamal Mubarak holds an 18 percent share in a subsidiary, EFG Hermes Private Equity. The bank said Gamal Mubarak's relationship with the company began in 1997, before he entered politics, and was made public at the time. The banks said it "does not manage funds for the Mubarak family, nor has it received - directly or indirectly - any benefits or special consideration from the Egyptian government."
Gamal Mubarak entered politics in 2000 and quickly rose to the top of his father's ruling National Democratic Party. He was fired from the party's political bureau last week in what appeared to be a failed attempt by the regime to buy time and defuse public anger.
While corruption complaints up to now have focused on former top officials, Egyptian lawyer Ibrahim Youssri said he is seeking a criminal investigation of the Mubarak family. Youssri said the general prosecutor agreed to meet with him Monday to review the evidence.
"This is a really positive sign," Youssri said.
Officials in the prosecutor's office were not immediately available for comment.
Egypt can only start the long process of recovering assets once it launches criminal investigations, said Daniel Thelesklaf, who heads the Basel-based International Center for Asset Recovery. After that first step, Switzerland can release bank information, to be followed by the return of assets following convictions, he said.
Last month, after the ouster of another Mideast autocrat, Tunisia's Zine Al Abidine Ben Ali, Switzerland froze the bank assets, estimated at $620 million, of former Tunisian government officials.
Thelesklaf said recovering assets has become easier in recent years, with the adoption of international anti-corruption conventions. Egypt is a signatory, and so are the United Arab Emirates, touted as a possible retirement refuge for Mubarak.
The responsibility lies with the Egyptian authorities to get an investigation started, said Thelesklaf, noting that other countries with limited resources, such as Haiti and Nigeria, have managed to repatriate public funds. "If Nigeria can do it, Egypt can do it," he said.
Associated Press writer Maggie Michael in Cairo and Raphael Satter in London contributed to this report.