The increasingly aggressive investigation into President Trump's former campaign manager, Paul Manafort, has raised new questions about whether the special counsel's expanding Russia probe could ultimately engulf more members of Trump's inner circle — and even the president himself.

And prosecutors' interest in a 2011 lawsuit against Manafort, which accused him of aiding in an international embezzlement scheme, could signal a new line of inquiry far beyond looking into Russian meddling in last year's presidential election.

Several people close to the process said Manafort's legal situation appears to be more precarious than that of anyone else currently under investigation by the special counsel. And unlike other former Trump associates who have caught the attention of congressional and Justice Department investigators — such as former adviser Carter Page, who played only a tangential role in the campaign — Manafort maintained a long and significant relationship with the president and his closest aides. His past proximity to Trump could cause the White House political headaches if Manafort ultimately faces criminal charges.

Special counsel Robert Mueller's investigators appear to be focused on Manafort's financial history and the political work he did for a now-exiled Ukrainian leader, people familiar with the matter told the Washington Examiner.

While some legal experts have speculated that the Justice Department's aggressive pursuit of Manafort could signal its intention to force him into testifying against Trump, two sources close to the investigation said Manafort faces a set of legal woes that have nothing to do with the president.

"No matter how much pressure Mueller brings to bear on Paul, nothing will make him manufacture evidence against President Trump," said one person close to Manafort.

Manafort's relationship with his legal team at WilmerHale ended this week, two sources confirmed to the Washington Examiner, after news that FBI agents had raided his home last month drew renewed scrutiny of the former campaign chief's situation. Manafort's new attorney, Kevin Downing of Miller & Chevalier, lists "money laundering," violations of the Foreign Corrupt Practices Act and "white collar matters" as his areas of expertise.

"It was entirely amicable and had nothing to do with Mueller. This was just about putting resources where they needed to be," the person said.

The FBI raid of Manafort's home escalated fears among Trump's allies that the investigation could uncover criminal activity or ensnare aides who worked with Manafort on the campaign.

"I do think that a couple of Trump advisers are in real trouble," a former Trump adviser who has been contacted by congressional investigators told the Washington Examiner.

The former adviser argued Mueller's team won't find any evidence of collusion between Trump associates and Russians because none occurred during the presidential race.

But he said the probe seems to have expanded to a financial inquiry that will likely involve an examination of Trump's business records, a situation that could expose the president to scrutiny and political controversy over any number of mistakes made during his decades-long, multi-billion dollar career in real estate.

"I would say that President Trump is in real danger. And not because of any collusion, there was none, but because of unrelated things," the adviser said. "I also believe that Manafort and [Gen. Mike] Flynn are in serious legal trouble. But I don't think anyone else is."

Flynn, Trump's former national security adviser, is under fire for failing to register as a foreign agent after doing consulting work for a Turkish company and failing to disclose payments he received from Russian entities.

Although Flynn registered retroactively as a foreign lobbyist in March, the documents he filed indicated his contract with the Turkish company, Inovo, was active during his time on the Trump campaign and revealed that Flynn worked for both entities at the same time.

Investigators have seemingly begun to reach out to individuals who encountered Manafort in his work for former Ukrainian President Viktor Yanukovych.

Former U.S. prosecutor Ken McCallion, who represented former Ukrainian Prime Minister Yulia Tymoshenko, Yanukovych's political rival, in a 2011 lawsuit against Manafort and others, told the Washington Examiner that he has given federal investigators emails and banking transactions that were included in Tymoshenko's lawsuit.

McCallion declined to go into specifics when asked about the information he provided, saying only that it was in response to "follow-up questions" about the lawsuit, which accused Manafort of helping a Ukrainian oligarch with strong ties to Russia move a mountain of cash into offshore real estate investments.

McCallion would not say when he was initially contacted by federal prosecutors and asked to hand over records related to the case.

Although an American judge threw out the lawsuit in 2015, investigators' current interest in the materials produced for that case could provide clues as to what Mueller hopes to learn about Manafort.

Tymoshenko accused Yanukovych's associates — including Manafort — of laundering roughly $3.5 billion in embezzled Ukrainian funds through "New York-based bank accounts and otherwise legitimate real estate and other investment activities" in the U.S., according to documents filed in the 2011 lawsuit she pursued against him and others involved in the alleged scheme. Tymoshenko claimed Manafort had worked for Yanukovych since 2003.

Reached by phone on Friday, Manafort's former business administrator refused to say whether she had been contacted by investigators and hung up on the Washington Examiner.

Several other former Manafort associates said they had not spoken with anyone from the Justice Department or declined to speak about their erstwhile colleague.

One attorney representing another person involved in the Russia probe suggested federal prosecutors' investigation of Manafort is far more serious than their inquiries into other Trump associates.

"My client is a million times remote from what they're investigating Manafort for," the attorney said. "My thread is so different, and none of the things we've been asked to turn over would even be congruent."

Manafort's ties to foreign lobbying efforts in Ukraine contributed to his ouster from the Trump campaign last year when stories about his past began to raise uncomfortable questions for the team.

However, his work in Ukrainian politics was not his first foray into foreign consulting. Manafort's records indicate he has done lobbying work for foreign governments and entities around the world since at least 1985, including in Kenya, South Korea, Angola, and Nigeria.

Manafort registered as a foreign agent with the Justice Department on June 27 for work he performed in Ukraine through his firm, DMP International. According to those documents, Manafort's company was hired by the Ukrainian Party of Regions, a pro-Russia political party, to "turn Ukraine into the most attractive state for investment in the region" and to create a "Western democratic political party" in Ukraine.

His firm's work in Ukraine stretches back at least nine years. Manafort inked a contract with Edelman, a major public relations firm, in 2008 to assist him in crafting a message for his Ukrainian clients.

Former Ukrainian President Viktor Yanukovych was a member of the Ukrainian Party of Regions when he won a hotly-contested election in 2010, and he served as president until the 2014 Ukrainian revolution led to his ouster and to the Russian annexation of Crimea, a Ukrainian territory.

It is unclear when Manafort began and ended his work with Yanukovych's party, and investigators are likely examining Manafort's records to determine exactly what kind of work he performed for the exiled Ukrainian leader and how much he was paid for it.

But news reports published at the time of Yanukovych's victory in 2010 and afterward suggest Manafort was instrumental in steering the Ukrainian politician to power and that he remained close to Yanukovych for years afterward.

When Yanukovych fled Kiev in Feb. 2014 with his country on the brink of a civil war, his aides dumped thousands of documents into a reservoir near his residence in an effort to conceal them from the public. But Ukrainian journalists waded into the water and recovered many of the papers, scanned them, and posted them online shortly afterward. Among the recovered files was a 2012 letter, written in Russian, in which an American lawyer preparing a report on the jailing of Yanukovych's former political opponent asked for Manafort's help obtaining government records.

The letter piqued interest in Washington at the time of its discovery three years ago, as it suggested Manafort was involved in guiding an independent assessment of the events that led to the controversial prison sentence given to Yulia Tymoshenko in 2011, shortly after she lost the Ukrainian election to Yanukovych, Manafort's client. Tymoshenko's jailing was widely viewed as a politically-motivated act of retaliation by her opponents, but the report did not ultimately characterize her prosecution as corrupt.

Manafort's work with Yanukovych erupted into a controversy last year when a black ledger from the former president's residence in Kiev surfaced. The ledger contained handwritten dates and transactions that suggested Manafort received off-the-books payments from the Ukrainian government, although it remains unclear whether money ever changed hands on the dates in question.

Yanukovych presently faces treason and corruption charges in Ukraine, although he remains exiled in Russia. The charges against him stem in part from his close relationship with Russian President Vladimir Putin and his reliance on the Russians in the events that led up to his ouster.