Former U.S. President Donald Trump's deputy press secretary, Sarah Matthews, attends a public hearing of the U.S. House Select Committee to investigate the January 6 Attack on the U.S. Capitol, on Capitol Hill, in Washington, U.S., July 21, 2022.
Former U.S. President Donald Trump's deputy press secretary, Sarah Matthews, attends a public hearing of the U.S. House Select Committee to investigate the January 6 Attack on the U.S. Capitol, on Capitol Hill, in Washington, U.S., July 21, 2022. Reuters / JONATHAN ERNST

The panel probing the Jan. 6, 2021, assault on the U.S. Capitol plans to push its investigation further in the coming weeks, interviewing additional members of Donald Trump's cabinet and his campaign, as well as U.S. Secret Service members, the committee's vice chair said on Sunday.

"We're not finished yet," Representative Liz Cheney, one of two Republicans on the U.S. House of Representatives' select committee, told CNN's "State of the Union."

In eight hearings over six weeks featuring testimony from former White House officials and Trump associates, the panel painted the former president as responsible for the attack on the Capitol in a bid to stay in power following his 2020 election loss. The hearings have also outlined efforts by Trump and his allies to overturn the election results.

The committee has yet to decide whether to make a criminal referral concerning Trump's conduct to the U.S. Justice Department, Cheney said, "but that's absolutely something we're looking at."

Cheney said testimony from Trump aides had opened doors to new evidence as others in the administration have come forward. The committee also continues to seek an interview with Virginia "Ginni" Thomas, the wife of U.S. Supreme Court Justice Clarence Thomas, over her role in Trump's efforts to overturn the election and may subpoena her if necessary, Cheney said.

Cheney said the panel will look into the deletion of text messages by the Secret Service, adding that the agency had not shown the kind of cooperation that was expected.

"The extent to which there are no text messages from the relevant period of time, the extent to which we have not had the kind of cooperation that we really need to have, those are all the things the committee is going to be looking at in more detail in the coming weeks," Cheney said in a separate interview on "Fox News Sunday."

Earlier this month, the committee subpoenaed the Secret Service, seeking text messages from Jan. 5 and Jan. 6, 2021, as it investigated accusations by a watchdog that they had been erased.

The Secret Service had said that data from some phones had been lost during a system migration that was initiated prior to the watchdog's request. It handed over some records to the panel on Wednesday and the committee said it wanted more data.