Former US Vice President Mike Pence has testified as part of a criminal investigation into Donald Trump’s alleged attempt to overturn his 2020 election loss.
Mr Pence, 63, sat before a federal grand jury in Washington DC for more than seven hours, sources told the BBC’s US affiliate CBS News.
He was subpoenaed to testify under oath earlier this year.
Prosecutors’ hearings took place behind closed doors.
His appearance on Thursday came hours after an appeals court rejected a last-ditch effort by Trump’s legal team to block Mr Pence from testifying.
Mr Pence’s lawyers tried unsuccessfully to challenge the subpoena, arguing that his role as Senate president during his tenure meant he was immune from Congress.
His final testimony, which has been solicited for months, is a major milestone in the two-year investigation, which is being led by special counsel Jack Smith, who was appointed by former war crimes prosecutor, Attorney General Merrick Garland.
The investigation is gathering evidence into whether Mr Trump and his allies broke federal law in trying to challenge the outcome of the 2020 election won by President Joe Biden.
It is also investigating the US Capitol riots on 6 January 2021, when Mr Trump’s supporters blockaded the building in an attempt to prevent the election results from being certified.
Mr Pence, who, like all vice presidents, was president of the Senate – a largely ceremonial role – could theoretically have derailed the final certification of the election result and delayed the transition of power.
Mr Trump publicly pressed his vice president to do so, and his refusal led Mr Pence to lash out.
Trump supporters chanted “Hang Mike Pence” as they stormed Congress and ransacked the corridors of the Capitol building as politicians, including Mr Pence, took refuge inside.
Mr Pence is considered a key witness in the trial, and although it was not immediately clear what he told the grand jury, prosecutors may have asked him about his interactions with Mr Trump and his team in the days and weeks leading up to the riots. .
“We will obey the law and we will tell the truth,” Mr Pence said in an interview with CBS on Sunday. “The story I tell the American people across the country … will be the story I tell in that organization.”
Mr Pence spoke publicly about the Capitol riots and the pressure he faced to challenge the election result. “President Trump is wrong. I have no right to cancel the election,” he said in a speech in February.
In his memoir, So Help Me God, Mr Pence wrote that Trump tried to pressure him to block the certification of the election results on the morning of the riots. “You will go down a genius,” the then-president told Mr Pence.
He accused Mr Trump of endangering his family and others in the Capitol, saying history would hold him “responsible”.
Mr Pence is reportedly considering his own presidential bid in 2024, which would see him directly challenge his former boss for the Republican nomination.
Mr Trump, who has launched his bid to return to the White House, was in New Hampshire on Thursday for a campaign event. Asked by NBC News about Mr Pence’s testimony, he commented: “I don’t know what he said, but I have a lot of confidence in him.”
The former president faces other legal problems, including another federal investigation led by Mr Smith into the possible mishandling of classified documents.
Georgia has a separate investigation into efforts to change the outcome of the 2020 election.