Update (2:15 pm ET): The leaks from the special counsel's office just keep coming. After reporting earlier today that AG Jeff Sessions sat for an interview with Mueller last week, the paper is now reporting that Mueller interviewed former FBI Director James Comey last year.

The interview with Comey focused on the infamous memo he wrote where he alleged that Trump had asked him to take it easy on Michael Flynn. Many of the special counsel's critics have warned that Mueller should recuse himself from all dealings with Comey, who is believed to be a key witness in the probe. Comey and Mueller have a long history of working together, and also share a personal friendship, having vacationed together.

A spokeswoman for Sessions confirmed that he had appeared before the committee.

Circling back to Sessions, the NYT pointed out that Sessions is perhaps one of the most important witnesses to be interviewed by Mueller.

For Mr. Mueller, Mr. Sessions is a key witness to two of the major issues he is investigating: the campaign’s possible ties to the Russians and whether the president tried to obstruct the Russia investigation. Mr. Mueller can question Mr. Sessions about his role as the head of the campaign’s foreign policy team. Mr. Sessions was involved in developing Mr. Trump’s position toward Russia and met with Russian officials, including the ambassador. Along with Mr. Trump, Mr. Sessions led a March 2016 meeting at the Trump International Hotel in Washington, where one of the campaign’s foreign policy advisers, George Papadopoulos, pitched the idea of a personal meeting between Mr. Trump and Mr. Putin. Mr. Papadopoulos plead guilty in October to lying to federal authorities about the nature of his contacts with the Russians and agreed to cooperate with the special counsel’s office.

The NYT didn't specify whether Comey was offered an opportunity to comment.

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Far from wrapping up his probe, Special Counsel Robert Mueller's team appears to have arrived at the senior tier of President Donald Trump's advisers early this year. After CNN reported that Steve Bannon agreed to a voluntary informal interview with Mueller and his team, the New York Times is reporting that Attorney General Jeff Sessions was questioned for several hours last week by Mueller and his team as part of the investigation into Russian meddling in the 2016 election.

However, unlike Bannon, the Sessions interview has a deeper significance: It marked the first time that investigators for the special counsel are known to have interviewed a member of President Trump's cabinet.

A spokeswoman for Sessions confirmed the story.

Sessions announced in March that he would recuse himself from all matters related to the 2016 election, including the Russia probe, before his deputy Rod Rosenstein appointed Mueller, a former FBI director, to be special counsel in charge of the investigation. Sessions aroused suspicion by neglecting to tell Congress that he met twice with Russian ambassador Sergey Kislyak during the campaign.

The NYT previously reported that Trump had lobbied Sessions not to recuse himself. Reports have surfaced in recent months that Mueller is pivoting his investigation to examine reports of obstruction of justice that have already been refuted by fired FBI Director James Comey.

Sessions was also deeply involved in Comey's firing, which occurred after Trump asked Comey to "let this go" - referring to the DOJ's investigation of former National Security Adviser Mike Flynn.

Sessions was accompanied by Chuck Cooper, a longtime Washington lawyer, to the interview. Mueller has brought charges against Flynn, former Trump Campaign executive Paul Manafort, Manafort's No. 2 Rick Gates and former Trump foreign policy adviser George Papadopoulos.