Prosecutor Jack Smith listens as Hashim Thaci, not pictured, makes his first courtroom appearance before a judge at the Kosovo Specialist Chambers court in The Hague, Netherlands, on November 9, 2020.
CNN  — 

Special counsel Jack Smith sat in on the federal grand jury proceeding while former Vice President Mike Pence testified for more than five hours last week, three sources familiar with the matter tell CNN.

Smith and Pence interacted while Pence was at the courthouse, and one source described the interaction as respectful.

Smith’s appearance is the first known time the special counsel has attended a grand jury proceeding in the investigation. Smith is leading the criminal probe with a team of prosecutors into the aftermath of the 2020 election and efforts to overturn the results.

Pence was poised to recount for the first time under oath his direct conversations with Trump leading up to January 6, 2021. Then-President Donald Trump repeatedly pressured him unsuccessfully to block the 2020 election results, including on the morning of January 6 in a private phone call.

A federal judge previously ruled Pence could be compelled to recount conversations the two men had where Trump may have been acting corruptly. Smith’s office had fought in sealed proceedings to force Pence to testify.

Pence’s meeting with investigators comes as he is exploring a possible challenge to Trump for the Republican presidential nomination in 2024, with his testimony likely to elicit a strong negative reaction from his former boss.

As part of his political appearances and a recent book tour, Pence frequently speaks about refusing to do Trump’s bidding on January 6 and instead followed the Constitution. But he had avoided speaking under oath as part of any investigation.

The special counsel’s office declined to comment, as did Marc Short, an adviser for the former vice president.

This story has been updated with additional information.