WASHINGTON (AP) — The explosive allegations at the center of an impeachment inquiry into President Joe Biden were false, federal prosecutors said, and came from an ex-FBI informant who said he was in touch with Russian intelligence.

The informant, Alexander Smirnov, is "actively peddling new lies that could impact U.S. elections," federal prosecutors said Wednesday, as they appealed to a judge to keep him behind bars ahead of trial on charges alleging he lied to the FBI about a phony multimillion-dollar bribery scheme involving the Bidens and the Ukrainian energy company Burisma.

Defense attorneys have not directly addressed prosecutors' claims about Russian intelligence contacts but said they look forward to defending him at trial. Republicans in Congress have distanced themselves from Smirnov's claims and resisted calls to end the impeachment inquiry.

Here's a look at what's known about Smirnov, the case against him and fears about potential effects on U.S. elections:

WHO IS ALEXANDER SMIRNOV?

Smirnov had been an informant since 2010, growing close to an FBI handler he spoke to "nearly every day," prosecutors said in court documents. He met with Burisma executives starting in the spring of 2017 because the company was interested in buying an American company and making an initial public offering on a US stock exchange, according to court documents.

Prosecutors say he has access to more than $6 million, with some money held in the name of his longtime partner. His recent reports to his handler included the guest lists from parties on mega yachts with Russian oligarchs, prosecutors said.

He holds dual Israeli-US citizenship and lived in Israel for more than a decade, later moving to Los Angeles and finally Las Vegas in 2022, prosecutors said.

WHAT IS HE ACCUSED OF?

Smirnov has been charged with falsely reporting that Burisma executives paid Hunter and Joe Biden $5 million each around 2015 after hiring Hunter Biden to sit on its board and "protect us" from an investigation by the then-Ukrainian prosecutor general. The charges were filed by the Justice Department special counsel who has separately filed gun and tax charges against Hunter Biden.

No evidence has emerged that Joe Biden acted corruptly or accepted bribes in his current role or previous office as vice president.

Smirnov, meanwhile, had only routine business dealings with Burisma, and they did not start until 2017 after the prosecutor general was gone and when Joe Biden was unable to influence U.S. policy since he was out of office, prosecutors said.

Smirnov "expressed bias" against Joe Biden before he made the bribery allegations in June 2020, years after they supposedly occurred, prosecutors said. An FBI field office investigated the allegations and recommended the case be closed in August 2020, according to charging documents.

Smirnov's defense attorneys have said he is presumed innocent, and they successfully pushed for his release from jail ahead of trial. U.S. Magistrate Judge Daniel Albregts in Las Vegas said Tuesday he was concerned about Smirnov's access to money but that federal guidelines require him to fashion "the least restrictive conditions" ahead of trial. Prosecutors are appealing that decision.

WHAT TIES ARE THERE TO RUSSIAN INTELLIGENCE?

Prosecutors laid out in court documents "extensive and extremely recent," contact Smirnov said he had with people aligned with Russian intelligence.

Smirnov had told his FBI handler that he had been in touch with "multiple" other foreign intelligence services, including officials linked to Russian intelligence, according to court documents.

As recently as December, court documents state he was relaying details about meetings with Russian officials, one of whom said the country's intelligence services had intercepted calls from prominent Americans that "the Russian government may use as 'kompromat' in the 2024 election, depending on who the candidates will be," using a word for compromising material.

That echoed a previous bogus story from months before when he pushed his handler to investigate whether Hunter Biden had been recorded in a Ukrainian hotel, prosecutors said. The president's son has never traveled to Ukraine, according to court documents.

"What this shows is that the misinformation he is spreading is not confined to 2020. He is actively peddling new lies that could impact U.S. elections after meeting with Russian intelligence officials in November," prosecutors wrote in court documents.

National security experts have warned for years that foreign governments — primarily Russia, China and Iran — want to undermine the U.S. and see elections as a way to do it.

In a threat assessment late last year, Microsoft warned Russia remains "the most committed and capable threat to the 2024 election," with the Kremlin seeing next year's vote as a "must-win political warfare battle" that could determine the outcome of its war against Ukraine.

WHAT ARE REPUBLICANS SAYING?

Smirnov'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.

They became a flashpoint in Congress in July as Republicans demanded the FBI release the unredacted form, a so-called FD-1023, documenting the unverified allegations. Republican Rep. James Comer of Kentucky had subpoenaed the form as Republicans deepened their probe ahead of the 2024 presidential election. Republicans acknowledged they couldn't confirm if the allegations were true but said they were significant in their investigation of Hunter Biden.

The allegations of Russian contact with the source of those allegations should be a death knell for the impeachment inquiry, said Democratic Rep. Jamie Raskin of Maryland. "It appears like the whole thing is not only obviously false and fraudulent but a product of Russian disinformation and propaganda," he said.

Republicans, on the other hand, have downplayed the importance of Smirnov's allegations. Judiciary Committee Chairman Rep. Jim Jordan, R-Ohio, pointed to Smirnov's long track record as an FBI source but said the impeachment inquiry goes beyond his allegations. The case against him "doesn't change the fundamental facts" at issue in the impeachment probe, he said.

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Associated Press writers Rio Yamat in Las Vegas, Christina A. Cassidy in Atlanta and video journalist Dan Huff in Washington contributed to this report.