As the fabulist New York Republican representative-elect George Santos prepares to be sworn in on Tuesday, Brazilian prosecutors say they are reopening a criminal fraud case against him.

Santos, who faces federal and state investigations involving possible criminal activity related to his two congressional campaigns, is accused of using a stolen checkbook and fake name at a clothing shop outside Rio de Janeiro in 2008, the New York Times reported on Monday citing court documents.

The case languished for more than a decade, however, as Brazilian authorities did not know where Santos was.

Santos reportedly told police in 2010 that he and his mother stole the checkbook from a man that she had once worked for, and then used it to make illicit purchases, per the Times.

He seemed to come clean about the purported fraud to the store’s proprietor the next year on a Brazilian social media website, allegedly writing: “I know I screwed up, but I want to pay.”

While a judge in Brazil greenlit a charge against Santos in 2011, he had already gone to the US. Because Brazilian authorities needed to officially notify him to the charges before the case could proceed, the case ground to a halt. Brazilian prosecutors will now file a petition in court asking that Santos respond to the charges, after which Brazil’s justice ministry will send it to the US justice department.

If convicted, the maximum penalty is five years imprisonment as well as a fine, the New York Times said.

Santos has insisted on his innocence. “I am not a criminal here – not here or in Brazil or any jurisdiction in the world,” he told the New York Post after the story was first revealed. “Absolutely not. That didn’t happen.”

Santos has admitted to lying about integral parts of his biography, such as claims that he worked for Goldman Sachs and Citigroup, as well as completing college. “My sins here are embellishing my résumé. I’m sorry,” Santos said.

He also tried to dispel criticism that he misrepresented having Jewish heritage. On Santos’s campaign website, he claimed that his mother was Jewish and that his grandparents fled the Nazi regime in the second world war.

Santos is now claiming that he is “clearly Catholic”, but that his grandmother recounted being Jewish and later becoming Catholic. “I never claimed to be Jewish,” he told the newspaper. “Because I learned my maternal family had a Jewish background I said I was ‘Jew-ish’.”

Santos has since faced calls to step down by some members of his own party. The Texas Republican representative Kevin Brady, formerly the ranking member of the House ways and means committee, said on Fox News that Santos “is certainly going to have to consider resigning”, while the outgoing Arkansas governor, Asa Hutchinson, recently said that Santos’s falsehoods were “unacceptable” and needed to be investigated by the ethics committee.