Cassidy Hutchinson, a top aide to former White House Chief of Staff Mark Meadows, is expected to testify in person at the Jan. 6 committee's surprise hearing, according to a source with direct knowledge of the plans.

Driving the news: Hutchinson, who was Meadows' most trusted aide, has been a crucial witness for the committee, offering an inside account of the West Wing in the days leading up to, on and in the aftermath of the Jan. 6 Capitol attack.

• Given her proximity to the chief of staff and her access to the inner workings of the White House, she had an extraordinary view into the events on Jan. 6, possibly including closed-door conversations and paper trails most staff were unaware of.
• Her planned testimony was first reported by Punchbowl News.

Why it matters: Hutchinson may be the most dangerous witness for Trump so far because, unlike many others who had paramount access to the former president, she is not directly or indirectly on the Trump payroll.

• Hutchinson doesn't depend on Trump to sign on political candidates as clients, nor does she work for a Trump-affiliated firm or think tank.
• Hutchinson told the committee she was present when Meadows described hearing Trump's positive reaction to the Capitol rioters calling for then-Vice President Mike Pence to be hanged.
• A pre-taped video of Hutchinson from her deposition with the committee was also shown at the panel's last hearing, during which she testified that six House Republicans lawmakers who worked to reject the counting of electoral votes on Jan. 6 sought pardons following the attack.

Between the lines: Hutchinson's switch of lawyers while being investigated by the committee — from Trump-aligned lawyer Stefan Passantino to former Justice Department official Jody Hunt — signaled she was no longer attached to Trumpworld.

What we know: Recent reports have detailed that Meadows burned papers in his fireplace following the Jan. 6 riot.

• The committee has been interested in knowing what those documents contained and what else Hutchinson heard and saw during those final days as Trump plotted to overturn the 2020 election.
• Hutchinson already appeared for multiple closed-door depositions, so the committee already knows how valuable her testimony is.
• The decision to bring Hutchinson before the panel for a formal hearing shows they believe the material she offers warrants upending their carefully crafted schedule to have her speak publicly in a highly televised setting.