The focus of an overarching Justice Department investigation into the Capitol insurrection last year has shifted to members of Trump’s orbit, with a "senior adviser" to former President Trump the next in line to receive a subpoena.

That aide — 31-year-old William Russell, who served as a special assistant and deputy director of presidential advance operations for the Trump administration — was with the former president for a time on January 6, 2021. He left the White House with the previous administration and moved to Florida to continue working for Trump, one of a few former staffers to do so.

According to CBS News, FBI agents in Florida paid a visit the aide to Russell’s home on Wednesday morning for questioning but didn’t find anyone there. They contacted him afterward and served him a subpoena via email.

Representatives for the senior Trump adviser ignored requests to comment on the subpoena.

The subpoena — as the New York Times reported Wednesday, citing unnamed sources — pertains to the grand jury investigation into the events that preceded the January 6, 2021 storming and ransacking of the U.S. Capitol by a mob of Trump supporters.

Federal investigators have expanded their probe into the failed months-long campaign by Trump and his cronies to overturn Joe Biden’s victory in the 2020 general elections.

Last week, Pat Cipollone, a former White House counsel, and Patrick Philbin, Cipollone's deputy, testified before the grand jury investigating Trump’s post-election efforts to cling to power. Cipollone and Philbin, multiple sources say, were in the room where key conversations around the former president’s election subversion efforts took place.

The grand jury has also heard testimony from two aides of former Vice President Mike Pence: Marc Short, Pence’s former chief of staff, and Greg Jacob, Pence’s former general counsel.

For weeks after his loss, Trump and his allies peddled egregious claims of election fraud in an all-out assault on the integrity of the election, giving rise to the assault on Congress meant to stymie the certification of a democratically elected candidate.

Preceding the insurrection, the Big Lie was, in the weeks before the certification of Biden’s electoral victory, accompanied by an audacious plan by Trump and his allies to install a slate of fake electors subservient to Trump in seven battleground states to overturn Trump’s loss.

The fake elector scheme, proposals to seize voting machines, and an attempt to strong-arm the Department of Justice into investigating voter fraud conspiracies were part of the broad Republican-led effort to overturn Trump’s loss, the Times noted in its report.

The Department of Justice is also entangled with Trump in a separate case involving the former president’s mishandling of classified government documents. On Monday, the judge in that case, a Trump appointee, granted the former president’s request to have a special master review the documents seized from Mar-a-Lago and shockingly halted the government’s review of the classified documents and assessment of national security risks.

The Justice Department notified Judge Aileen Cannon on Thursday of its intention to appeal her ruling.