Republican US Representative Liz Cheney will serve as vice-chairwoman of the congressional select committee investigating the deadly 6 January assault on the US Capitol, the panel announced on Thursday.

The announcement is likely to increase criticism of Cheney, a three-term House member and the daughter of former Republican Vice President Dick Cheney, from lawmakers closely aligned with former president Donald Trump.

One of the two Republican select committee members, Cheney was stripped of her leadership role in the House Republican caucus after denouncing Trump’s false assertions that his 2020 presidential election loss to Joe Biden was not legitimate.

House Democrats formed the committee, despite objections from Trump’s fellow Republicans in the House, to investigate the assault on the Capitol by mobs of his supporters as Congress was meeting to certify Democrat Biden’s election victory.

Nearly 600 people have been arrested in connection with the attack.

It was the worst violence at the seat of the US government since the British invasion during the war of 1812. Four people died on the day, one shot to death by police and the others died of natural causes. A Capitol police officer attacked by protesters died the following day. Four police officers who took part in the defense of the Capitol later took their own lives. More than 100 police officers were injured.

The committee has already begun its work. It held a first hearing in July, with emotional testimony from police who fought off the rioters. And in August, it announced two massive requests for documents related to the events of 6 January – one from Trump associates and government agencies and another from social media firms.

CNN reported on Wednesday – before the announcement about Cheney’s new role on the panel – that the hardline conservative House Freedom Caucus planned to send a letter to the House Republican leader, Kevin McCarthy, seeking to remove Cheney and Representative Adam Kinzinger, the other Republican select committee member, from the Republican conference – the caucus of party members in the chamber – for their roles on the panel.