The long-awaited investigation into the 6 January insurrection will begin on Tuesday, when a House special committee convenes to investigate the deadly attack on the US Capitol.

It has been more than six months since hundreds of Donald Trump supporters stormed the Capitol in a bid to prevent Joe Biden’s confirmation as president, and two months since Senate Republicans blocked a bipartisan plan to establish an independent commission to explore the attack.

That left Nancy Pelosi, the Democratic House speaker, to create a select committee that has become the focus of an unsavory political row, with Republican leadership turning down the opportunity to participate and attempting to boycott proceedings.

What is the committee investigating?

The committee will attempt to uncover what led to hundreds of people gaining access to the bastion of US democracy, including who organized the attack and who may have funded it.

One of the aims, Pelosi has said, is to consider “how we must organize ourselves to prevent anything like it from ever happening again”.

Jamie Raskin, who led the prosecution in Trump’s second impeachment trial, said the committee will focus on “why we were not prepared for the president to unleash the violence against us and what that means in terms of security”.

Who is the committee chair?

Bennie Thompson, Democratic congressman from Mississippi and the chair of the House homeland security committee, will lead proceedings.

“We have to get it right,” Thompson told the Associated Press on Monday. He said if the committee can find ways to prevent anything like it from happening again: “Then I would have made what I think is the most valuable contribution to this great democracy.”

Pelosi chose Thompson as chairman after he crafted bipartisan legislation with John Katko, a Republican representative from New York, that would have created an independent, bipartisan commission to investigate the attack.

Thompson is the only Democrat in the Mississippi delegation to the House.

What can we expect on Tuesday?

Four police officers will provide the first public testimony. The officers “are expected to testify about their experiences of both physical and verbal abuse on January 6”, according to the Washington Post.

“I think we need to pay close attention to what they’re saying,” said Thomas Manger, the new chief of the US Capitol police, to CBS on Sunday.

The officers were on duty as Trump supporters swarmed the Capitol. More than 100 officers were injured during the attack, and two died by suicide in the days that followed. A third officer, Brian Sicknick, collapsed and later died after engaging with the protesters. A medical examiner determined he died of natural causes.

Who else will appear before the committee?

Thompson told the Guardian he wanted to interview senior Trump administration officials who were in the Oval Office as the riot unfolded, from Mark Meadows – then the White House chief of staff – to Trump’s daughter Ivanka.

Thompson said he was prepared to issue subpoenas and launch lawsuits should any witnesses refuse to appear.

“We will pursue it in court,” he said.

The committee chair suggested Trump himself could even be called as a witness. The committee is keen to investigate a call between Trump and House minority leader Kevin McCarthy that took place as the riot progressed.

Who is on the committee?

The committee has 13 seats, but as of Monday afternoon only nine had been filled. Seven Democrats, including Adam Schiff, the chair of the House intelligence committee; Zoe Lofgren, one of the impeachment managers who presented the case against Trump in 2020; and Pete Aguilar, vice chair of the House Democratic caucus.

Pelosi appointed Liz Cheney, an anti-Trump Republican who has been ostracized by the GOP, to the committee on 1 July. On Sunday, Pelosi said Adam Kinzinger, another Republican critical of Trump, would serve on the committee.

Why are there so few Republicans on the committee?

Pelosi invited Kevin McCarthy to select five GOP members. McCarthy chose Jim Jordan and Jim Banks – staunch Donald Trump allies who deny his role in the attack and objected to the certification of Biden’s win – among his nominees. Pelosi rejected the pair, and McCarthy then withdrew all his candidates. Democrats have accused McCarthy of attempting to undermine the investigation.