Pat Cipollone, Trump’s White House counsel, could help the panel flesh out important moments.

Pat A. Cipollone, President Donald J. Trump’s second and final White House counsel, appeared for a videotaped, transcribed interview with the House Jan. 6 committee last week after being subpoenaed, and his testimony could help the panel flesh out episodes at the heart of its investigation.

Mr. Cipollone — who also sat for an informal interview with the committee in April — was present for several key meetings related to Mr. Trump’s efforts to retain power and subvert the results of the 2020 election. Several witnesses have described Mr. Cipollone as opposing those efforts at critical moments.

In particular, Mr. Cipollone was at a meeting on Dec. 18, 2020, in the Oval Office. During that meeting, Mr. Trump entertained proposals from his former national security adviser, Michael T. Flynn; a lawyer, Sidney Powell; and Patrick Byrne, the former chief executive of Overstock.com, to use the military or the Department of Homeland Security to seize voting machines to look for electoral fraud.

Since Mr. Cipollone’s informal appearance in April, the committee has heard from many additional witnesses. One of them — Cassidy Hutchinson, a former aide to Mark Meadows, the White House chief of staff in the final year of the Trump administration — provided the committee with extensive testimony about Mr. Trump’s actions and statements ahead of the Capitol riot and during it, as well as about conversations she said she had with senior advisers.

Ms. Hutchinson described a conversation with Mr. Cipollone in which he cautioned against Mr. Trump traveling to the Capitol with his supporters after his planned speech at a rally at the Ellipse, near the White House.

In Ms. Hutchinson’s telling, Mr. Cipollone warned that “we’re going to get charged with every crime imaginable if we make that movement happen.”

Two people close to Mr. Cipollone said he did not recall that conversation, and that the committee had been alerted before his testimony last week that he would not confirm it had taken place.

Instead, the committee focused on soliciting testimony from Mr. Cipollone that could support information they had gathered from other witnesses.

According to two people familiar with his appearance, Mr. Cipollone was asked about discussions related to presidential pardons in the final weeks of the presidency. He was also asked his opinion of Mr. Trump’s false claims of widespread fraud, as well as Mr. Trump’s attacks on Vice President Mike Pence.