Attorney General Jeff Sessions was interviewed by special counsel Robert Mueller last week as part of Mueller's on-going Russia investigation. According to Yahoo News, the interview was related to Donald Trump's firing of FBI Director James Comey. Mueller is investigating potential collusion between the Russian government and the Trump campaign during the 2016 presidential election, and is also looking into whether the Trump administration obstructed justice and attempted to hamper the investigation.
The New York Times reports the Attorney General is the first cabinet member to be interviewed as part of the investigation. Sessions could be a key witness for Mueller because he was directly involved in Trump's controversial decision to fire Comey. The White House claimed the firing was not related to the FBI's investigation. They cited a memo from Deputy Attorney General Rod Rosenstein that "faulted Comey for his handling of the Hillary Clinton email server investigation, as justification for the dismissal."
Jeff Sessions was forced to recuse himself from the investigation into Russia after he failed to mention meetings he had with Russian officials during his Senate confirmation hearings. He said that he could not oversee an investigation into the campaign that he was an early supporter of. That move angered Trump, and almost lead to the Sessions resigning as Attorney General.
The meeting with Sessions comes as Mueller secured cooperation of Trump's former chief strategist Steve Bannon. He was subpoenaed to appear in front of a grand jury, but later agreed to be interviewed by investigators.