An 800-page report set to be released on Thursday by House investigators will conclude that Donald Trump criminally plotted to overturn his 2020 election defeat and “provoked his supporters to violence” at the Capitol with false voter fraud claims.

Before the release, on Wednesday night, the January 6 committee released 34 transcripts from 1,000 interviews conducted over 18 months. Most of the interviewees were witnesses who invoked their fifth-amendment right against self-incrimination.

More transcripts and some video were also expected to be released.

“I guarantee there’ll be some very interesting new information in the report and even more so in the transcripts,” Adam Schiff of California, a Democratic member of the committee, told CBS.

Subjects of the interview transcripts released on Wednesday included Jeffrey Clark, a senior official in the Trump justice department who worked to advance Trump’s efforts to overturn the election, and John Eastman, a conservative lawyer and an architect of Trump’s last-ditch efforts to stay in office.

Each invoked his fifth-amendment right against self-incrimination.

Also included in the release was testimony from witnesses associated with extremist groups involved in planning the attack. The Oath Keepers founder, Stewart Rhodes, convicted last month of seditious conspiracy, and the former Proud Boys leader Enrique Tarrio both spoke to the committee. Tarrio and four other members of the extremist group will appear in court on similar charges this month.

Committee members hope for criminal charges against Trump and key allies. Only the justice department has the power to prosecute, so the panel sent referrals recommending investigation of Trump for four crimes, including aiding an insurrection.

At the meeting on Monday to adopt the report and recommend charges, the Democratic chair, Bennie Thompson of Mississippi, said: “This committee is nearing the end of its work but as a country we remain in strange and uncharted waters.

“We’ve never had a president of the United States stir up a violent attempt to block the transfer of power. I believe nearly two years later, this is still a time of reflection and reckoning.”

On Wednesday, Thompson was asked by MSNBC if he had confidence the Department of Justice would pursue charges.

He said: “I am more comfortable with the fact that the special counsel” – the prosecutor Jack Smith, appointed last month – “has been actively engaged in pursuing any and all the information available. They have been in contact with our committee, asking us to provide various transcripts and what have you.”

Thompson was asked if the committee was cooperating with the justice department.

He said: “Yes … we made the decision [with] consultation with other members that we will cooperate. But early on … we felt we had to get the report done. We had to get it filed, which we’ll file on Thursday morning, so the whole public will have access to it.

“There were people that we deposed that justice had not deposed. There were electors in various states that justice couldn’t find. We found them.

“We deposed them. And so we had a lot of information, but now we make all that information available to [the justice department]. And if they come back and want to interview staff or any members, ask any additional information, we’ll be more than happy to do it.”

According to the report’s executive summary, which was released on Monday, “the central cause of January 6 was one man, former president Donald Trump, who many others followed. None of the events of January 6 would have happened without him.”

The report’s eight chapters of findings will largely mirror nine hearings that presented evidence from interviews and millions of pages of documents. The 154-page summary detailed how Trump amplified false claims on social media and in public, encouraging supporters to travel to Washington and protest Joe Biden’s win, and how he told them to “fight like hell” at a rally in front of the White House then did little to stop them as they beat police, broke into the Capitol and sent lawmakers running.

It was a “multi-part conspiracy”, the summary concluded.

Trump is running again for the presidency but faces multiple investigations, including into his role in the insurrection and the presence of classified documents at his Florida estate. A House committee is expected to release his tax returns, documents he has fought to keep private. He has been blamed by Republicans for a poor showing in the midterm elections, leaving him politically vulnerable.

Most Republicans have stayed loyal but the January 6 hearings were watched by tens of millions.

Trump slammed the committee as “thugs and scoundrels”. In response to the criminal referrals, he said: “These folks don’t get it that when they come after me, people who love freedom rally around me. It strengthens me.”

Republicans take over the House on 3 January. The committee will be dissolved.