Alexander Smirnov was, in many ways, the archetype of an informant operating in the shadowlands of the former Soviet Union — a profiteer, fixer and gossip who promoted his ability to make sense of a confusing landscape to American law enforcement agencies.
For more than a decade, he played a double game, giving the F.B.I. tantalizing visibility into a cast of oligarchs and public officials while offering himself as a consultant, with a hard-to-define skill set, to some of the same people he was keeping tabs on.
Then he stepped over the line.
In 2020, Mr. Smirnov told his F.B.I. handler what prosecutors say was a brazen lie — that the oligarch owner of the Ukrainian energy company Burisma had arranged to pay $5 million bribes to both President Biden and his son Hunter. The explosive claim was leaked to Republicans, who made Mr. Smirnov’s allegations a centerpiece of their now-stalled effort to impeach President Biden, apparently without verifying the allegation.
Last week, Mr. Smirnov, 43, was indicted on charges that he lied to investigators about the Bidens. He was arrested as he was preparing to leave for what prosecutors called “a monthslong, multicountry foreign trip” during which he claimed to have plans to meet with contacts from multiple foreign intelligence agencies.
In court filings, prosecutors working for David C. Weiss, the special counsel investigating Hunter Biden, described Mr. Smirnov as a serial liar who could not even be trusted to describe honestly his own occupation or account for his finances.
Congressional Democrats predicted that the indictment would kill the impeachment push. Lawyers for Hunter Biden seized on it to try to undermine the tax and gun cases Mr. Weiss has brought against him. In a court filing, they contended that Mr. Smirnov’s false claims “infected” the cases, and suggested, without providing evidence, that prosecutors reneged on a plea deal last summer because they had followed “Mr. Smirnov down his rabbit hole of lies.”
How Mr. Smirnov managed to convince business partners, law enforcement agencies and politicians that he had something of value to offer remains as much of an enigma as the man now at the center of the saga.
Little is known about Mr. Smirnov beyond a few public records and snippets of biography in papers filed in federal court in Las Vegas, where he lives and was taken into custody on Thursday. He appears to have no presence on social media, and he covered his face as he walked out of detention on Tuesday, wearing a leather jacket and orange shoes.
(He was released on Tuesday by a federal judge after paying a personal recognizance bond and surrendering his U.S. and Israeli passports. Prosecutors filed an appeal on Wednesday to that decision, citing the risk he posed to national security.)
Mr. Smirnov, a dual citizen of Israel and the United States, moved into a three-bedroom, three-bath condo off the Las Vegas Strip that his longtime girlfriend bought two years ago for $980,000. There is no public record of prior criminal charges against him in the United States.
Before that, he lived for at least 16 years in California, most recently in the affluent seaside community of Laguna Beach.
It is not clear, either in court filings or public records, where Mr. Smirnov was born. He is fluent in Russian, speaks English with a heavy accent and might have roots in Ukraine, according to a person with knowledge of the situation.
In court filings this week, his lawyers portrayed him as a law-abiding resident of Nevada with a valid driver’s license and a “stable residential history.” He suffers from a severe, unspecified problem with his eyes that requires regular treatment.
“Mr. Smirnov has had seven surgeries in the last year, is required to take prescription medication daily and requires ongoing care,” wrote David Z. Chesnoff, his lawyer.
His lawyers cited his close personal connections with three people — his longtime girlfriend, Diana Lavrenyuk, her grown son in the District of Columbia area, and a cousin from Miami, Linor Shefer — to counter claims by prosecutors that he would flee the country if released.
Ms. Shefer — who was crowned “Miss Jewish Star” in Moscow in 2014 at a pageant officiated by Israel’s ambassador to Russia, according to the Jewish Telegraphic Agency — declined to comment when reached on her cellphone early Thursday.
The special counsel’s office did little to fill in any of these biographical blanks, in part because prosecutors appeared uncertain whether anything he told them was true.
In a memo arguing for his indefinite detention, deputies to Mr. Weiss described him as a perpetual fabulist. He not only fed the F.B.I. bogus information about the Bidens and misled prosecutors about his wealth, estimated at $6 million, but also told officials there that he worked in the security business, even though the government could find no proof that was true.
Mr. Chesnoff, in a brief interview, said his client had misunderstood the government’s questions about his finances, and had reported only his modest personal wealth without including the more substantial holdings in business accounts.
Even while sharing some of the startling information he relayed to his handlers — including a claim that he had been fed unspecified information about Hunter Biden from Russia’s intelligence services — prosecutors cast doubt on anything he told the F.B.I.
“The misinformation he is spreading is not confined” to his false claims about the Bidens, prosecutors wrote.
“He is actively peddling new lies that could impact U.S. elections after meeting with Russian intelligence officials in November,” they added.
Nonetheless, some level of mendacity is expected among informants working in a part of the world where misinformation is commonplace, forcing law enforcement officials to sift for germs of useful intelligence.
A federal prosecutor involved in screening claims about Mr. Biden’s foreign work testified last year that Mr. Smirnov was an “important confidential human source” who “had been used in other investigations.”
But court documents show that law enforcement officials have long harbored doubts about the veracity of Mr. Smirnov’s reports and assertions he made about his associations that seemed intended to overstate his importance.
And many of his most provocative claims, outlined in Justice Department documents, have not yet been publicly verified.
For instance, he appears to have told the F.B.I. that a business associate who introduced him to Burisma executives had ties to Russian organized crime, according to notes of this conversation, which do not indicate whether there is proof of the claim.
It is the sort of raw intelligence that law enforcement routinely collects and vets behind closed doors before determining whether to act on it, and the investigation into Hunter Biden’s foreign business dealings attracted so much of it that the Justice Department created a special intake process.
But Mr. Smirnov’s allegations made their way to congressional Republicans, who forced the release of raw F.B.I. notes chronicling the bribery claims and featured them prominently in the impeachment push.
Yet while Mr. Smirnov’s indictment provided a rare public relations boost to Hunter Biden — who is scheduled to appear before a House committee next week — Mr. Smirnov’s claims are not mentioned in the indictments of Mr. Biden.
And there is no evidence they were central to Mr. Weiss’s investigation of Mr. Biden’s foreign business dealings and finances, which drew upon financial records and grand jury interviews with a number of associates.
Pashtana Usufzy contributed reporting from Las Vegas.
