Alexander Smirnov falsely reported to the FBI in June 2020 that executives associated with the Ukrainian energy company Burisma paid Hunter and Joe Biden $5 million each in 2015 or 2016, prosecutors said in an indictment. Smirnov told his handler that an executive claimed to have hired Hunter Biden to “protect us, through his dad, from all kinds of problems,” according to court documents.

Prosecutors say Smirnov in fact had only routine business dealings with the company in 2017 and made the bribery allegations after he “expressed bias” against Joe Biden while he was a presidential candidate.

Smirnov, 43, appeared in court in Las Vegas briefly Thursday after being charged with making a false statement and creating a false and fictitious record. He did not enter a plea. The judge ordered the courtroom cleared after federal public defender Margaret Wightman Lambrose requested a closed hearing for arguments about sealing court documents. She declined to comment on the case.

The informant’s claims have been central to the Republican effort in Congress to investigate the president and his family, and helped spark what is now a House impeachment inquiry into Biden. An attorney for Hunter Biden, who is expected to give a deposition later this month, said the charges show the probe is “based on dishonest, uncredible allegations and witnesses.”

The top Democrat on the House Oversight Committee, Rep. Jamie Raskin of Maryland, called for an end to the Biden impeachment inquiry.

Raskin said the allegations from the Republicans against Biden “have always been a tissue of lies built on conspiracy theories.” He called on Speaker Mike Johnson, Oversight Committee Chairman James Comer and House Republicans “to stop promoting this nonsense and end their doomed impeachment inquiry.”

Comer, R-Ky., downplayed the importance of the informant, who had figured centrally to the start of the probe.

“To be clear, the impeachment inquiry is not reliant on the FBI’s FD-1023,” Comer said in a statement, referring to the form documenting Smirnov’s allegations.

The chairman said the inquiry “is based on a large record of evidence, including bank records and witness testimony,” including interviews this week. He said the committee will continue to “follow the facts” and determine whether to proceed with articles of impeachment against Biden.

In the indictment, prosecutors say that Smirnov had contact with Burisma executives, but it was routine and actually took place took place in 2017, after President Barack Obama and Biden, his vice president, had left office — when Biden would have had no ability to influence U.S. policy.

Smirnov “transformed his routine and unextraordinary business contacts with Burisma in 2017 and later into bribery allegations against Public Official 1, the presumptive nominee of one of the two major political parties for President, after expressing bias against Public Official 1 and his candidacy,” the indictment said.

He repeated some of the false claims when he was interviewed by FBI agents in September 2023 and changed his story about others and “promoted a new false narrative after he said he met with Russian officials,” prosecutors said.

If convicted, Smirnov faces a maximum penalty of 25 years in prison.

The charges were filed by Justice Department special counsel David Weiss, who has separately charged Hunter Biden with firearm and tax violations.

The Burisma allegations became a flashpoint in Congress as Republicans pursing investigations of President Joe Biden and his family demanded the FBI release the unredacted form documenting the allegations. They acknowledged they couldn’t confirm if the allegations were true.

Comer had subpoenaed the FBI last year for the so-called FD-1023 document as Republicans deepened their probe of Biden and his son Hunter ahead of the 2024 presidential election.

Working alongside Comer, Republican Sen. Chuck Grassley of Iowa released an unclassified document that Republicans at the time claimed was significant in their investigation of Hunter Biden. It added to information that had been widely aired during Donald Trump’s first impeachment trial involving Trump attorney Rudy Giuliani’s efforts to dig up dirt on the Bidens ahead of the 2020 election. After Grassley released the document, the White House said the claims in it had been “debunked for years.”

The impeachment inquiry into Biden over his son’s business dealings has lagged in the House, but the panel is pushing ahead with its work.

Hunter Biden is expected to appear before the committee later this month. His attorney, Abbe Lowell, said he had long warned the probe was based on “lies told by people with political agendas, not facts. We were right and the air is out of their balloon.”

A judge set a detention hearing for Feb. 20 for Smirnov, who was arrested at the Las Vegas airport after arriving in the U.S. from overseas.