Former White House chief of staff Reince Priebus was interviewed Friday by special counsel Robert Mueller’s team of investigators as part of an ongoing investigation into potential coordination between Russia and the Trump campaign, his attorney said.

“He was happy to answer all of their questions,” the lawyer, William Burck, said in a statement.

It was not immediately clear what questions Priebus was asked or how long the interview lasted.

Priebus is one of several current and former White House aides expected to be interviewed by Mueller’s team in the coming weeks. Those investigators, besides looking into whether campaign aides coordinated with the Kremlin to influence the outcome of the presidential election, are also looking into a series of White House actions since the start of the administration, including the firing in May of former FBI Director James Comey.

They’re also investigating the short-lived tenure of former national security adviser Michael Flynn, who was forced to resign in February, and the drafting of a public statement about a June 2016 meeting between Donald Trump Jr. and a Russian lawyer at Trump Tower in New York.

As head of the Republican National Committee during the presidential campaign, Priebus would have insight into the inner workings of the Trump campaign, particularly during the general election. He also was present during the presidential transition and served as White House chief of staff during times crucial to Mueller investigation, including while Flynn served in the administration and while Trump made the decision to fire Comey.

In a prepared statement in June to the Senate intelligence committee, Comey described how Priebus had briefly interrupted a private White House conversation with the president in which he said Trump told him he hoped Comey would end an FBI investigation into Flynn and his contacts with the Russian ambassador.

“After he had spoken for a few minutes about leaks, Reince Priebus leaned in through the door by the grandfather clock and I could see a group of people waiting behind him,” Comey’s statement said. “The President waved at him to close the door, saying he would be done shortly. The door closed.”

Priebus, who was ousted from his position in July, did not answer his cell phone Friday evening. His voicemail box was full.

Mueller has requested a large batch of documents from the White House. Among the other officials his team is expected to interview are former press secretary Sean Spicer and White House counsel Don McGahn.

(AP)