(AP) Special counsel Robert Mueller's office has charged a wealthy Russian lawyer with making false statements to the FBI, according to a court filing unsealed on Tuesday.

Alex van der Zwaan, the lawyer, is well-connected and represents the interests of a number of Russian oligarchs. He is also the son-in-law of German Khan, a Ukrainian-Russian billionaire and businessman.

Van der Zwaan was charged with "willfully and knowingly" making "false, fictitious, and fraudulent statements and representations" to federal investigators about his work for the law firm Skadden, Arps, Meagher, & Flom LLP and Associates in 2012. The firm was employed by the Ukraine Ministry of Justice to compile a report about the trial of former Ukrainian Prime Minister Yulia Tymoshenko.

Tymoshenko was jailed in 2011 after being convicted by the Ukrainian government of abuse of power. Her trial and subsequent conviction were criticized by human-rights groups and deemed politically motivated by the US, the UK, German, Italy, Spain, and other European countries.

Skadden was roped into the controversy when it emerged that Ukraine's former Justice Minister, Oleksandr Lavrynovych, embezzled over $1 million in order to pay the law firm, which was hired by then Ukrainian president Viktor Yanukovych.

Yanukovych, a pro-Russian strongman from Ukraine's Party of Regions, hired Skadden to justify the proceedings against Tymoshenko — who was his political opponent — to the US government.

After being pressured by US and Ukrainian prosecutors, Skadden refunded about half the amount it was paid to the Ukrainian government. Mueller's focus on the Skadden case was first reported last September.

Van der Zwaan is also charged with misrepresenting his communications with Rick Gates, the former deputy manager of President Donald Trump's campaign.

According to the document, van der Zwaan is accused of making false statements about his last communication with Gates, which took place in mid-August 2016 and consisted of an "innocuous text message."

Van der Zwaan is also accused of lying to investigators about why he did not turn over a September 2016 email between himself and another individual referred to in the charge as "Person A" to Mueller's office.

Per the court filing, van der Zwaan not only spoke to both Gates and "Person A" about Skadden's report on Tymoshenko's trial, but also destroyed evidence Mueller's office was seeking, including the September 2016 email.

Gates served as the deputy under former Trump campaign chairman Paul Manafort, who has long drawn scrutiny over his shady financial dealings and ties to pro-Russia interests that stretch back over a decade. Mueller's office is expected to announce a plea deal with Gates within the next few days, under which Gates has reportedly agreed to testify against Manafort.

Gates met Manafort nearly three decades ago while he was an intern at Black, Manafort, Stone, Kelly — one of the most powerful lobbying firms in DC. Manafort left the firm the same year Gates joined, but they reunited in 2006 at Manafort's new consulting company, Davis Manafort.

Gates joined the Trump campaign in early 2016, when Manafort became the campaign chairman. Manafort was forced to step down as Trump's campaign chairman in August 2016, but Gates stayed and worked on Trump's transition team. He was ousted from a pro-Trump lobbying grouplast April amid questions about Russia's election interference, but he continued to visit the White House as late as June, according to The Daily Beast.

Meanwhile, Manafort, who was once described as an international "gun for hire" when it came to advancing Russian interests, has long been a focus of Mueller's investigation over his murky ties.

When Trump first hired Manafort in March 2016, Manafort was known for having worked as a top consultant to Yanukovych, and is widely credited with helping him win the election in 2010.

Yanukovych was ousted from the presidency in 2014 amid widespread protests against his Russia-friendly positions and his decision to back out of a deal that would have promoted closer ties between Ukraine and the West, and distanced it from Russia.

Yanukovych fled to Russia as the demonstrations escalated and grew bloody, and he is now living under the protection of the Kremlin. Since then, Ukrainian prosecutors investigating the protests have said that Yanukovych ordered security forces to open fire on protesters, and some are looking into whether Manafort had a hand in encouraging Yanukovych.

Manafort also had his share of financial entanglements with entities related to Russia when he joined the Trump campaign.

NBC News reported last March that Manafort was associated with at least 15 bank accounts and 10 companies in Cyprus. And The New York Times discovered in August 2016 that the Party of Regions designated nearly $13 million in undisclosed cash payments in Manafort's name.

The Atlantic also published several emails last year that appeared to show Manafort using his elevated role in the Trump campaign to resolve a financial dispute with Russian oligarch Oleg Deripaska. Manafort reportedly wrote an email to his associate, Russian-Ukrainian operative Konstantin Kilimnik, offering to give Deripaska "private briefings" about the campaign to "get whole." Former intelligence officials said the emails bore all the hallmarks of a quid pro quo operation.

Moreover, Manafort was one of three top Trump campaign officials who attended a June 2016 Trump Tower meeting with two Russian lobbyists who offered the campaign dirt on then-Democratic candidate Hillary Clinton.