The special counsel Robert Mueller has secured sworn testimony from George Nader, a little-known but critical witness in the Russia investigation.

Nader serves as an adviser to the United Arab Emirates' Crown Prince Mohammed bin Zayed Al-Nahyan and attended two meetings with President Donald Trump's associates that have invited intense FBI scrutiny.

In particular, investigators are focused on a January 2017 meeting in the Seychelles islands between Nader, Trump associate Erik Prince, and Kremlin ally Kirill Dmitriev, the head of a sanctioned Russian investment fund.

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George Nader, a Middle East expert connected to several associates of President Donald Trump, is now cooperating with the special counsel Robert Mueller and has testified before a grand jury in the Russia investigation, The New York Times reported Tuesday.

FBI investigators approached Nader when he landed at Washington Dulles International Airport in January and served him with search warrants and a grand jury subpoena, the report said. At the time, Nader was en route to Mar-a-Lago to meet with President Donald Trump and his associates to celebrate the anniversary of Trump's first year in office.

Nader's inclusion in the Russia probe stems from his involvement in two meetings he attended as an adviser to and representative of the United Arab Emirates' Crown Prince Mohammed bin Zayed Al-Nahyan. The first meeting took place in New York in December 2016, and the second in the Seychelles islands in January 2017.

New details about the meetings and Nader's involvement contained in the Times report provide critical clues about the timeline of Trump-Russia contacts, as well as the degree to which the president's closest and highest-ranking associates were involved.

December 2016 Trump Tower meeting

The crown prince traveled to New York during the transition period in December 2016 and reportedly met with former national security adviser Michael Flynn, Trump’s son-in-law and senior adviser Jared Kushner, and former White House chief strategist Steve Bannon at Trump Tower.

The meeting was said to have raised red flags within the US intelligence community because the government was not notified of Crown Prince Mohammed’s visit. The Obama administration felt misled by the UAE as a result, which prompted then-national security adviser Susan Rice to request that Trump associates’ names be unmasked in intelligence reports detailing the meeting.

A senior Middle East official acknowledged to CNN last year that the UAE did not inform the US of the crown prince’s visit in advance but denied that the UAE had misled the Obama administration. The official said that the December Trump Tower meeting was merely part of an effort to build a relationship with the incoming administration.

Mueller's prosecutors have repeatedly questioned Nader about the meeting, as well as his meetings in the White House with Kushner and Bannon following Trump's inauguration.

That same month, Kushner met with Sergei Kislyak, then Russia's ambassador to the US, and reportedly proposed setting up a secure back-channel of communication between Trump and Moscow using Russian facilities.

Shortly after, Kushner had a separate meeting with Sergei Gorkov, the CEO of the sanctioned Russian state-owned bank Vnesheconombank, which was reportedly orchestrated by Kislyak. The interaction piqued investigators' scrutiny as the FBI began examining whether Russian officials suggested to Kushner that Russian banks could finance Trump associates' business ventures if US sanctions were lifted or relaxed.

Kushner's meeting with Gorkov came as he was looking for investors to shore up financing for a building on Fifth Avenue in New York that his family's real-estate company had purchased.

Jared Kushner, senior White House adviser, listens during a county sheriff listening session with U.S. President Donald Trump, not pictured, in the Roosevelt Room of the White House in Washington, D.C., U.S., on Tuesday, Feb. 7, 2017. Andrew Harrer/AP

January 2017 Seychelles meeting

In addition to Nader's meeting with Kushner, Bannon, and Flynn in December 2016, investigators are also keenly interested in another meeting he attended that took place in the Seychelles islands shortly after the Trump Tower gathering.

Following that meeting, Blackwater founder and Trump associate Erik Prince approached the crown prince and told him he was authorized to act as an unofficial surrogate for Trump, according to The Washington Post. He then asked Crown Prince Mohammed to set up a meeting with Kirill Dmitriev, the head of a US-sanctioned Russian investment fund who is closely allied with Russian President Vladimir Putin.

The meeting took place on January 11, 2017 in the Seychelles islands. While Nader attended the meeting as Crown Prince Mohammed's representative, Emirati officials believed Prince represented the Trump team and that Dmitriev represented Putin.

The meeting's purpose was to create a back-channel of communication between Trump and Russia, and UAE officials also participated in the hopes of helping to encourage Russia to distance itself from Iran, a major Kremlin ally, according to The Post.

The Trump administration has often expressed skepticism toward Iran and Trump has pushed hard to scrap the US’s nuclear deal with Iran.

Nader’s presence at the January 2017 Seychelles meeting is what landed him in the crosshairs of the special counsel, who is investigating Russia’s interference in the 2016 US election and whether members of the Trump campaign colluded with Moscow to tilt the race in his favor. Nader, according to The Times, also once worked as a consultant to Blackwater.

Prince told the House Intelligence Committee last year that he knew Dmitriev was a Russian fund manager but did not know it was a sanctioned fund that was controlled by the Russian government.

Prince also denied that he attended the meeting as an official representative of the incoming administration, saying instead that he traveled to the Seychelles to meet with potential business customers from the UAE. During the meeting, Prince told lawmakers on the panel, the customers “mentioned a guy who I should also meet who was also in town,” who turned out to be Dmitriev.

When he met Dmitriev, they discussed a range of topics, and Dmitriev stressed that he wished Russia and the US could resume normal trade relations, Prince said.

After the Seychelles meeting, Dmitriev also met with Anthony Scaramucci, who would later become the White House communications director, at the World Economic Forum in Davos, Switzerland.

Russian state media quoted Scaramucci as saying, after his meeting with Dmitriev, that the Obama administration's new sanctions on Russia — which were imposed that month to penalize it for interfering in the 2016 election — were ineffective and detrimental to the US-Russia relationship.

US softens its stance on Russia sanctions

Russia’s economy was dealt a stinging blow in 2014, when the US imposed sweeping sanctions to punish Russia for its aggression toward neighboring Ukraine and its annexation of Crimea.

Dmitriev's company, the Russian Direct Investment Fund, was included on the list of Russian economic entities that were penalized as part of that decision.

An RDIF spokesperson reached out to Business Insider to clarify that the fund was included on the US sanctions list because of its status as a former subsidiary of Vnesheconombank.

The UAE, meanwhile, has invested in a number of projects along with RDIF as part of an effort to foster closer ties to Russia.

The Obama administration announced another round of sanctions in December 2016, as a penalty for Russia's meddling. The US government also shuttered two Russian diplomatic facilities in the country and expelled 35 Russian diplomats.

After Obama left office, Congress overwhelmingly voted to impose new sanctions on Russia last summer, which Trump signed into law after facing public pressure from lawmakers and critics who accused him of catering to Putin's wishes.

However, the White House declined to enforce the law this year. The State Department said that the law's mere existence was enough to penalize Russia, because it had already made a dent in Russian defense sales.

“From that perspective, if the law is working, sanctions on specific entities or individuals will not need to be imposed because the legislation is, in fact, serving as a deterrent,” a State Department spokesperson said.

Editor's Note: A previous version of this article stated the UAE holds a significant stake in RDIF, according to The Times' reporting. It was edited after an RDIF spokesperson reached out to Business Insider to clarify that the UAE is not a significant RDIF stakeholder, but rather that the two entities jointly invested in a number of projects together.