The indictment of Alexander Smirnov, a former FBI informant, is roiling the ongoing impeachment inquiry being led by House Republicans against President Joe Biden.
Smirnov, once touted as a star witness by Republicans, was charged last week for allegedly making false statements about Biden and his son Hunter, including a story about both men taking $5 million in bribes from Burisma, a Ukrainian energy company.
New Justice Department court documents unveiled Tuesday allege Smirnov told investigators that Russian intelligence officials were involved in passing the story.
MORE: Hunter Biden informant charged with lying had high-level Russian contacts: Documents"I think the Smirnov revelations destroy the entire case," Rep. Jamie Raskin, the top Democrat on the House Oversight Committee, told ABC News Senior Justice Correspondent Pierre Thomas on Wednesday.
"Smirnov was the foundation of the whole thing," Raskin continued. "He was the one who came forward to say that Burisma had given Joe Biden $5 million, and that was just concocted in thin air."
Republican Rep. Jim Jordan, chairman of the House Judiciary Committee, was also pressed by ABC News' Thomas about the allegations surrounding Smirnov.
"Well, all I'm saying is you got to ask the FBI about that," Jordan said. "He may, in fact, have given false I don't know. But what I do know is everything we knew ahead of time."
Jordan also told reporters that the Smirnov development "doesn't change the fundamental facts."
The comments came as the House Oversight Committee gathered Wednesday for a closed-door deposition with James Biden, President Biden's brother. James Biden told lawmakers the president "has never had any involvement or any direct or indirect financial interest" in his family's business ventures.
The Republican chairman of the Oversight Committee, James Comer, also sought to downplay the impact the Smirnov allegations would have on the impeachment probe.
In a statement last week, Comer said the "inquiry is not reliant" on Smirnov.
"It is based on a large record of evidence, including bank records and witness testimony, revealing that Joe Biden knew of and participated in his family's business dealings," Comer said.
MORE: James Biden tells House committee that his brother 'has never had any involvement' in his business dealingsRepublicans have alleged that President Biden was directly involved in and benefited from his family's business dealings -- accusations staunchly denied by the White House -- though they have not found evidence of a crime committed by the president.
Since formalizing the impeachment inquiry in mid-December, Republicans have held one public hearing and interviewed other witnesses, some of whom have similarly said President Biden wasn't involved in his family's business endeavors.
"It was that foundation that the whole house of cards has been built on and the entire thing has collapsed," Raskin said Wednesday of the Smirnov revelations. "But of course, we don't even have to rely on Smirnov's own words because there have been somewhere near a dozen witnesses who have completely repudiated and refuted these essential allegations."