PricewaterhouseCoopers, now called PwC, acted as her accountant, consultant and tax adviser, working with at least 20 companies controlled by her or her husband. Yet there were obvious red flags as Angolan state money went unaccounted for, according to money-laundering experts and forensic accountants who reviewed the newly obtained documents.

When the Western advisory firms came into Angola almost two decades ago, they were viewed by the global financial community as a force for good: bringing professionalism and higher standards to a former Portuguese colony ravaged by years of civil war. But ultimately they took the money and did what their clients asked, said Ricardo Soares de Oliveira, an international politics professor at Oxford who studies Angola.

“They are there as all-purpose providers of whatever these elites are trying to do,” he said. “They have no moral status — they are what you make of them.”

Now, more than two years after her father stepped down after 38 years as Angola’s strongman president, Ms. dos Santos is in trouble.

Last month, an Angolan court froze her assets in the country as part of a corruption investigation, along with her husband’s and those of a Portuguese business associate. The Angolan attorney general claimed the couple were responsible for more than $1 billion in lost state funds, with particular focus on De Grisogono and Sonangol.

Ms. dos Santos and her husband could face years in prison if convicted, according to the office of Angola’s president, João Lourenço. At the heart of the inquiry: $38 million in payments from Sonangol to a Dubai shell company hours after Angola’s new president announced her firing. Ms. dos Santos’s half brother is also facing corruption charges for helping to transfer $500 million from Angola’s sovereign wealth fund. The asset freeze came soon after I.C.I.J. reporting partners asked the government about transactions in the documents.

In an interview with the BBC, Ms. dos Santos, 46, denied any wrongdoing and called the inquiry a “political persecution.” “My companies are funded privately, we work with commercial banks, our holdings are private holdings,” she said.