The House impeachment managers and their team of lawyers are examining materials, including videos, photos and social media posts, for possible links between individuals close to Trump and some involved in the riot at the Capitol, a source with knowledge of the House impeachment managers' investigation told ABC News.
They include a newly surfaced video first reported by ABC News showing longtime Trump adviser Roger Stone in Washington, D.C., the morning of Jan. 6. In the video, Stone is flanked by members of the Oath Keepers militia group just hours before the deadly Capitol riots -- including one man who appeared to later have participated in the Capitol assault, according to online researchers.
"So, hopefully we have this today, right?" one supporter asks Stone in the video. "We shall see," Stone replies. Stone has maintained that he played "no role whatsoever in the Jan. 6 events" and has repeatedly said that he "never left the site of my hotel until leaving for Dulles Airport" that afternoon.
Examining the actions of Trump, his aides and allies before and during the riot could help House impeachment managers make their case that the 45th president's comments to supporters at a Jan. 6 rally outside the White House were the culmination of a weekslong effort to overturn the election results. It could also shed light on the actions of those around Trump and whether they could have been more familiar with the riot -- and some of those who participated in it -- than initially disclosed.
An ABC News investigation into the nearly 200 accused rioters facing federal charges for their involvement at the Capitol -- based on court and military records, interviews and available news reports -- found that at least fourteen individuals who stormed the Capitol building have since said they were following Trump's encouragement.
Democrats also are working to piece together what Trump did behind closed doors the day of the insurrection, sources familiar with the matter tell ABC News.
Impeachment investigators are looking into the actions of former senior staffers to Trump, including former White House chief of staff Mark Meadows, and what action they may or may not have taken related to the Capitol attack, the sources said.
Reached by ABC News on Friday, a spokesman for Meadows declined to comment.
Trump was only away from the White House for less than two hours, leaving only to speak to his supporters gathered at the "Save America" rally when he told them to head to the Capitol and repeatedly urged them to fight for him.
ABC News previously reported that when Trump returned to the White House, he moved between the private dining room and the Oval Office, watching the events play out in real time as a small group of advisers, including Meadows, urged the president to condemn the violence.
While Democrats are expected to extensively cite video and social media records from Jan. 6, it's not clear whether they will be able to call witnesses who could shed new light on Trump's actions around and during the riot.
The Senate has yet to strike an agreement on the contours of the trial, and whether either side can call witnesses to testify -- a move that would certainly extend proceedings in the Senate.
Impeachment managers on Thursday invited Trump to testify in his trial under oath, a surprise offer that Trump's legal team rejected and dismissed as an unconstitutional "public relations stunt," pointing to Trump's current status as a private citizen.
"Despite his lawyers' rhetoric, any official accused of inciting armed violence against the government of the United States should welcome the chance to testify openly and honestly -- that is, if the official had a defense," Rep. Jamie Raskin, D-Md., the lead House impeachment manager, said in a statement Thursday night.
"We will prove at trial that President Trump's conduct was indefensible. His immediate refusal to testify speaks volumes and plainly establishes an adverse inference supporting his guilt," Raskin said.