House Democrats released three new transcripts Monday as they charge closer towards the open hearing phase of their impeachment inquiry later this week.

The release included the transcript of Laura Cooper, top Defense official who oversees Ukraine, who testified about the Trump administration's decision to withhold nearly $400 million in aid to Ukraine, which Democrats are examining as part of the House investigation into whether President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE pressed Ukraine to help his own reelection bid in 2020.

And Democrats also released the transcripts from joint depositions with Catherine Croft and Christopher Anderson, two former assistants to former U.S. Special Envoy to Ukraine Kurt Volker.

While all three are more minor witnesses who were called into testify, they offered background information for House investigators as they seek to determine whether Trump used the aid or the promise of a White House meeting as leverage to get Ukrainian President Volodymyr Zelensky to open probes into interference in the 2016 presidential election and former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE, one of his top 2020 political rivals.

Cooper's testimony was primarily memorable for a GOP protest that delayed it.

A group of congressional Republicans protesting the closed-door depositions disrupted the scheduled hearing by storming the secure closed space in which the interview was set to be conducted.