Special Counsel Robert Mueller’s probe has expanded beyond Russia to the Middle East.

Mueller’s investigators have questioned a shadowy businessman about attempts by the United Arab Emirates to funnel money to the Trump campaign to buy political influence, The New York Times reported.

George Nader, a Lebanese-American adviser to the U.A.E’s de facto ruler, became a target of the Mueller investigation after he visited the White House numerous times last year.

The federal prosecutors reportedly want to know if Nader has been working to influence the Trump administration’s policy decisions on behalf of the U.A.E.

The 58-year-old has long been considered an enigmatic figure in Washington.

Once a publisher of an obscure magazine called Middle East Insight, Nader managed to worm his way into the Clinton administration as a back-channel negotiator with Syria.

“In the 1990s, George was a very effective under-the-radar operator in the peace process,” Martin Indyk, former American ambassador to Israel and a member of a team that Clinton created to negotiate peace deals between Israel and its neighbors, told The Times.

“Then, he disappeared.”

Nader eventually resurfaced in Washington as a man with ties to Mohammed bin Zayed, the crown prince of Abu Dhabi and the U.A.E.’s de facto ruler.

Nader was so well-connected that he received a report from top Trump fund-raiser Elliott Broidy about a private oval office meeting with the President, The Times reported.

Broidy, who runs a private security company with hundreds of millions in contracts with the U.A.E., eagerly discussed a new paramilitary force he was creating for the Emiratis.

Broidy also urged Trump to hold a meeting “in an informal setting” with the crown prince to support hawkish U.A.E policies and to fire Secretary of State Rex Tillerson, The Times reported.