The House January 6 hearings into the attack on the Capitol may not yet have found their John Dean – the White House counsel who turned on President Richard Nixon during Watergate – but in Cassidy Hutchinson they have turned up a surprisingly potent witness.

Hutchinson was an executive assistant to Mark Meadows, Donald Trump’s last chief of staff, and a special assistant to the president for legislative affairs.

In taped testimony, she has described Trump’s approval of chants from Capitol rioters about hanging the then vice-president, Mike Pence, and attempts by Republicans in Congress to have Trump issue pardons before leaving office.

On Tuesday, she is expected to testify in person – the first former Trump White House employee to do so.

According to Hutchinson’s LinkedIn page, she studied political science and American studies at Christopher Newport University, a public school in Virginia. Hutchinson’s page also follows St Andrew’s Episcopal school, in Austin, Texas.

While in college, Hutchinson interned at the Trump White House. In October 2018, she told her student newspaper she was “brought to tears when I received the email that I had been selected to participate”, and called the internship “an honor and a tremendous growing experience”.

Hutchinson also interned and for two powerful figures on the hard right of a hard-right party: Steve Scalise, the House Republican whip, and the Texas senator Ted Cruz.

According to the Washington Post, Hutchinson recently switched lawyers, swapping a former Trump White House ethics lawyer for an attorney with links to Jeff Sessions, the former Alabama senator who became the attorney general Trump fired in 2018.

That move, the Post said, indicated a new willingness to cooperate with the January 6 committee.

Hutchinson’s former boss, Meadows, first flirted with cooperating with the committee then refused to do so. The committee referred him to the Department of Justice (DoJ), for criminal contempt of Congress. The DoJ declined to pursue charges.

In the absence of testimony from Meadows, Hutchinson’s voice has come to the fore in a series of explosive hearings.

Earlier this month, Norm Eisen, a former ethics tsar in the Obama White House, told the Post: “Cassidy Hutchinson might turn out to be the next John Dean.”