By all appearances, the summer of 2020 was a very good time for George Santos. He was pulling in a six-figure salary from a Florida-based investment firm, and he had won the Republican Party’s support as a first-time candidate contesting a Long Island House seat.

Yet that June, Mr. Santos presented the State of New York with a very different story. According to federal prosecutors, he falsely claimed that he was unemployed in order to twist open a spigot of pandemic-era jobless benefits that eventually amounted to $24,000.

For the entirety of his public life, Mr. Santos has been a man shrouded in myths. He cast himself as a self-made American success story, spinning audacious lies about university degrees, fast cars and vast wealth. And when that persona unraveled, fellow politicians and the media fixated on the idea that he was a criminal mastermind evading detection.

The searing 13-count indictment unveiled by federal prosecutors from the Eastern District of New York on Wednesday cut through all of that. It cemented a story closer to “The Great Gatsby,” “The Talented Mr. Ripley” or other mainstays of a popular subgenre of frauds that snakes like a corrupt seam through American life.

In prosecutors’ telling, George Santos, defendant, is just another grifter with a taste for fame and designer goods, willing to lie and defraud wealthy people to get what he wants. That the stage happens to be politics seems incidental: As a two-time congressional candidate, he took advantage of donors, state officials and even the House of Representatives.

“It feels like a particularly American story,” said Amy Reading, a historian of American cons, before referencing Mr. Santos’s work for a Florida firm cited by the S.E.C. for wrongdoing. “Here you have someone who worked for an actual Ponzi scheme, while falsely claiming unemployment benefits in a global pandemic, and then he fell up to Congress.”

Former Senator Alfonse D’Amato, a Long Island Republican whose name graces the courthouse where Mr. Santos was arraigned, was more blunt.

“He’s a two-bit thief,” he said. “He is dead in the water. They got him good.”

Mr. Santos has already begun fighting that narrative. Though he has admitted to some lies, he pleaded not guilty in a packed courthouse on Long Island to all 13 counts, including money laundering, wire fraud, false statements and stealing public funds. Then he walked outside to reaffirm his intention to seek re-election.

“The reality is, this is a witch hunt,” Mr. Santos, 34, said, invoking another old American motif. “This is the beginning for me of the ability to address and defend myself.”

The indictment prompted a new round of calls by rank-and-file Republicans for Mr. Santos to resign or to even be expelled from Congress, but it remains far from clear if the political system will exact a price.

House Speaker Kevin McCarthy of California, who cannot afford to lose a single vote from his spare Republican majority, has already said that he has no intention of trying to push Mr. Santos out of office unless or until he is convicted at trial. That stance fits with House precedent in recent cases involving Republicans like Jeff Fortenberry of Nebraska and Chris Collins of New York but could take years to play out.

Democrats do have the ability to force a vote on expelling Mr. Santos from the House, but they would need dozens of Republicans to defy Mr. McCarthy and join them to meet the required vote threshold. For now, they have trained their attention on pressuring Mr. McCarthy to act on his own.

“This is not somebody who was afforded an opportunity to get rich quick and couldn’t resist the temptation,” said Representative Daniel S. Goldman, a Democrat and former federal prosecutor from Manhattan. “This is someone who is a premeditated serial liar, whose total existence is a lie and a fraud.”

Voters may be the first to issue a verdict of Mr. Santos. Republican leaders in New York and Nassau County, who supported him just two years ago, plan to back a primary challenger next year. They have a history of lining up money and volunteers to see their candidates through.

“He’s out, no matter how you do it, because we have a good party in Nassau County,” Edward F. Cox, the chairman of New York’s Republican Party, said.

But Mr. Cox, the son-in-law of former President Richard M. Nixon, added a note of frustration, too. “He will make a fortune out of the attention that has been given to him,” he said.

Mr. Cox was not the only critic of Mr. Santos left uneasy by the indictment. In shining a light on his misconduct, prosecutors indirectly illuminated the many ways in which political, financial and media institutions failed to weed out people like him. In fact, there was no indication federal prosecutors were investigating Mr. Santos before The New York Times and other news media began documenting his widespread lies and unusual financial dealings in December.

Since then, the news media has assembled a remarkable catalog of lies by Mr. Santos.

There is the fake résumé, fabricated down to the rapid growth he helped achieve at a major bank he never worked for and the 3.89 GPA he earned at a college he never attended. He claimed — falsely — that some of the people killed in the Pulse nightclub shooting in Orlando, Fla., were his employees. He told Nassau County Republican leaders he was part of a champion volleyball team at Baruch, the college he did not attend. He lied about houses he said he was building and sports cars he said he owned.

And then there were the reports that he raised money to pay for lifesaving surgery for a veteran’s dog, only to keep the money, and that he took part in an illegal card-skimming scheme.

There were hints in the 20-page indictment that prosecutors may still be digging through the tangled web of Mr. Santos’s financial life. It included work for the Florida investment firm accused of operating a Ponzi scheme; campaign finance reports riddled with irregularities; and attempts to broker the sale of luxury goods between wealthy businessmen he met through his political campaign.

The indictment also provided new details about three distinct schemes that prosecutors said Mr. Santos undertook in recent years.

They charged him with two counts of making false statements on personal financial disclosure reports that he had submitted to the House, by misstating the source of his income and then by overstating it.

The unemployment benefits scheme resulted in two counts of wire fraud and one count of stealing public funds.

The most complicated scheme laid out in the indictment involved Mr. Santos, a fake super PAC and a pair of wealthy Republican donors.

Beginning in September 2022, prosecutors said, Mr. Santos and a political operative working for him began pushing the donors to make large donations. In email and text messages, they falsely told the donors that the company was a super PAC working “exclusively” to elect Mr. Santos by buying TV ads.

In fact, it was a limited liability company, and after the two donors wired $25,000 each just days before the election, Mr. Santos pocketed the money himself. Prosecutors said he had used it to buy designer clothing and to pay off debts. None of the money went to the campaign.

Mr. Santos’s next court appearance is set for June 30, but his attention to another legal matter beckons sooner. Brazilian authorities have revived a 2008 case in which Mr. Santos was accused of using a stolen checkbook to buy $700 in clothes at a small clothing store in Brazil, and a hearing on the matter is scheduled for Thursday.