Liz Cheney, the Republican vice-chair of the panel, delivered the revelation at the conclusion of the committee’s seventh public hearing on the Capitol attack.

Rep. Liz Cheney, the vice chair of the House select committee investigating the Jan. 6 attack on the U.S. Capitol, said at Tuesday's public hearing that former President Donald Trump tried to contact a witness who has not yet publicly appeared before the committee.

"Let me say one more time, we will take any effort to influence witness testimony very seriously," Cheney said. 

Cheney said Trump tried to call this person, who did not pick up and did not respond. Instead, they alerted their lawyer. The lawyer alerted the committee, and Cheney said they have turned the matter over to the Justice Department.

Trump spokesman Taylor Budowich tweeted after Tuesday's hearing alleging that the media has become "pawns of the Unselect Committee."

"Liz Cheney continues to traffic in innuendos and lies that go unchallenged, unconfirmed, but repeated as fact because the narrative is more important than the truth," Budowich wrote. 

Rep. Jamie Raskin, who was one of the leaders of Tuesday's hearing, told reporters afterwards that there has been a "problem with a pattern of witness tampering from the beginning." He called it a "very serious offense."

"It is a crime to tamper with witnesses, and we want that message to go out, so no one can say that they're surprised by that," Raskin said.

At the hearing two weeks ago, Cheney said some of the witnesses who have appeared before the committee have received messages from some members of Trump's inner circle. She read some of the texts, including one that said "he wants me to let you know he's thinking about you. He knows you're loyal."

She said one witness told the panel they received phone calls. 

"What they said to me is, as long as I continue to be a team player, they know that I'm on the team, I'm doing the right thing, I'm protecting who I need to protect, you know, I'll continue to stay in good graces in Trump World," Cheney said, quoting the witness. "And they have reminded me a couple of times that Trump does read transcripts, and just to keep that in mind as I proceeded through depositions and interviews with the committee."

Another witness, according to Cheney, said they received a call during which the caller said, "[A person] let me know you have your deposition tomorrow. He wants me to let you know that he's thinking about you. He knows you're loyal, and you're going to do the right thing when you go in for your deposition."

"Most Americans know that attempting to influence witnesses to testify untruthfully presents very serious concerns," Cheney said in closing, noting the committee will be discussing how to proceed.

The House Jan. 6 committee has spoken to over 100 witnesses, and 15 have so far testified in seven public hearings. They have also shown clips from recorded testimony from other witnesses, including former Attorney General William Barr, Trump White House counsel Pat Cipollone, Ivanka Trump and Jared Kushner.