Former US vice president Mike Pence has appeared before a federal grand jury investigating former president Donald Trump’s role in efforts to overturn the 2020 election, according to reports.
Mr Pence was inside the US District Court in Washington for more than seven hours on Thursday, NBC News reported.
Security was beefed up at the federal courthouse and a sniffer dog was spotted in the hallway.
His testimony – behind closed doors – comes less than 24 hours after a federal appeals court rejected a last-ditch appeal by Mr Trump’s legal team to block his appearance.
Mr Pence is also reportedly exploring a possible challenge to Mr Trump for the Republican presidential nomination in 2024.
Mr Trump launched his third bid for the US presidency in November.
Incumbent Democrat president, Joe Biden, also confirmed he will run again in 2024 this week.
Mr Pence’s testimony on Thursday is a significant development in the Justice Department’s investigation and is likely to give prosecutors a key first-person account of certain conversations and events in the weeks preceding the deadly attack on the US Capitol.
Asked about his testimony, Mr Trump, who was at a campaign event in New Hampshire, told NBC News: “I don’t know what he said, but I have a lot of confidence in him.”
Mr Pence is considered a major witness in the criminal investigation led by Jack Smith, a former war crimes prosecutor.
“We’ll obey the law, we’ll tell the truth,” Mr Pence said in an interview with CBS News aired on Sunday.
“And the story that I’ve been telling the American people all across the country, the story that I wrote in the pages of my memoir, that’ll be the story I tell in that setting.”
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Mr Pence has spoken extensively about Mr Trump urging him to reject President Biden’s election victory in the days leading up to 6 January 2021, including in his book, So Help Me God.
“For four years, we had a close working relationship. It did not end well,” he wrote, summing up their time in the White House.
He has previously defended his actions on that day, after Mr Trump had claimed that a vice president had the authority to overturn the election results.
“President Trump is wrong. I had no right to overturn the election,” Mr Pence, who has often shied away from confronting his former boss, said in March.
“And his reckless words endangered my family and everyone at the Capitol that day, and I know history will hold Donald Trump accountable.”
Mr Smith is separately investigating Mr Trump over the potential mishandling of hundreds of classified documents at his Mar-a-Lago estate in Palm Beach, Florida, as well as possible efforts to obstruct that probe.