US attorney general Jeff Sessions has been interviewed as part of the investigation into alleged collusion between Donald Trump’s 2016 presidential campaign and Russia.
The Justice Department confirmed on Tuesday he was interviewed for hours last week, but declined to reveal details.
Special counsel Robert Mueller is leading the investigation into contacts between Mr Trump’s 2016 campaign and Russia.
Mr Sessions is believed to be the highest-ranking Trump administration official and first cabinet member to be interviewed by Mr Mueller’s team.
The probe is also examining whether the President’s actions since taking office, such as firing FBI director James Comey, were an obstruction of justice.
Like the President, Mr Sessions has repeatedly downplayed the notion that meddling from Russia helped get Mr Trump elected.
It is thought Mr Sessions could be an important witness because the President said he fired Mr Comey last May following a recommendation from the Justice Department.
At the time, Mr Comey was called out by Mr Sessions’ deputy Rod Rosenstein over his handling of the Hillary Clinton email investigation.
Mr Trump then said he was thinking of “this Russia thing” when he fired Mr Comey.
In March 2017, Mr Sessions recused himself from the investigation after acknowledging that he had two previously undisclosed encounters with Russian ambassador Sergei Kislyak during the campaign.
Mr Sessions was also in charge of the campaign’s foreign policy advisers, including George Papadopoulos, who has many Russian contacts and tried to set up a meeting between Mr Trump and Russian President Vladimir Putin.
Mr Papadopoulos admitted to making false statements to the FBI about his contacts.