The congressional panel investigating last year's Capitol riot has issued a legal summons ordering former President Donald Trump to testify to lawmakers.
Addressing him, the document reads: "You were at the center of the first and only effort by any US President to overturn an election."
It goes on: "You knew this activity was illegal and unconstitutional."
A lawyer for Mr Trump accused the lawmakers on the committee of "flouting norms".
The former president has lambasted the inquiry as a ruse designed to distract voters from the "disaster" of Democratic governance with US midterm elections looming next month.
Mr Trump could face criminal charges if he does not comply with the subpoena.
He has until 4 November to provide documents to the 6 January committee, and must appear for deposition testimony on or about 14 November.
If Mr Trump refuses to testify to Congress or hand over the requested material, the committee could refer the matter to the Department of Justice - potentially triggering criminal proceedings.
The subpoena was issued just hours after former Trump strategist Steve Bannon was fined $6,500 (£5,800) and sentenced to four months in jail for contempt of Congress.
He was convicted after refusing to give the committee testimony or documents.
Another Trump aide, Peter Navarro, is due to stand trial for contempt of Congress next month after refusing to co-operate with a similar subpoena.
The select committee is looking into Trump supporters' violent storming of the US Capitol building on 6 January, 2021.
The panel's seven Democrats and two Republicans unanimously voted last week to force the Republican to testify about his role in the riot.
Lawmakers say Mr Trump egged on his supporters to reject the 2020 presidential election result, leading them to storm the halls of Congress in an effort to prevent Joe Biden from being certified as the winner.
In a letter that accompanied the subpoena, chairman Bennie Thompson and vice-chairwoman Liz Cheney said the committee had "assembled overwhelming evidence, including from dozens of your former appointees and staff, that you personally orchestrated and oversaw a multi-part effort to overturn the 2020 presidential election".
"You took all of these actions despite the rulings of more than 60 courts rejecting your election fraud claims and other challenges to the legality of the 2020 presidential election, despite having specific and detailed information from the Justice Department and your senior campaign staff informing you that your election claims were false, and despite your obligation as President to ensure that the laws of our nation are faithfully executed," the letter added.
Mr Trump's legal team slammed the subpoena.
"We understand that, once again, flouting norms and appropriate and customary process, the Committee has publicly released a copy of its subpoena," said lawyer David Warrington.
"As with any similar matter, we will review and analyse it, and will respond as appropriate to this unprecedented action."
If Republicans retake control of the House of Representatives after November's midterm elections - which is widely expected - the 6 January committee's work will come to an end and the panel will be disbanded.
Ms Cheney - the top Republican on the panel and the daughter of former Republican vice-president Dick Cheney - will leave in January after losing a primary race in August to a Trump-backed challenger. The committee's only other Republican member, Adam Kinzinger, plans to retire at the end of this congressional session.