On December 28, 2022, Newsday reported that Nassau County District Attorney Anne Donnelly had opened an investigation into Devolder-Santos' actions. On March 2, 2023, the House Ethics Committee announced that it was investigating whether or not Devolder-Sanots had violated financial disclosure laws, violated conflict of interest laws, or engaged in unlawful activity. The probe also seeks to determine whether or not Devolder-Santos engaged in sexual misconduct. Reopening of case in Brazil (2022-2023) The New York Times reported that, in 2010, Santos was charged with check fraud while living in Brazil. According to Brazilian authorities, as of December 2022, the case remained unresolved. On January 2, 2023, the New York Times reported that Brazilian authorities were planning to revive the case against Santos. On December 26, 2022, Santos denied the charges. Santos said, "I am not a criminal here — not here or in Brazil or any jurisdiction in the world." On May 11, 2023, Santos signed a non-prosecution agreement with prosecutors in Brazil.

Devolder-Santos' campaign website said his mother had been born in Brazil after his grandparents had "fled Jewish persecution in Ukraine, settled in Belgium, and again fled persecution during WWII." Devolder-Santos also claimed his grandparents had survived the Holocaust. On December 21, 2022, multiple media outlets reported that, according to public records, both of Devolder-Santos' maternal grandparents were born in Brazil before World War II. CNN and other news outlets also reported that there was no evidence of Devolder-Santos having Ukrainian or Jewish heritage. On December 27, Forward reported that Devolder-Santos described himself as a "proud American Jew" in a position paper shared by his campaign. In a November 10 interview with Jewish Insider, Devolder-Santos described himself as a non-observant Jew. In an interview with the New York Post, Devolder-Santos said he never claimed to be Jewish. Devolder-Santos said. "I am Catholic. Because I learned my maternal family had a Jewish background I said I was ‘Jew-ish.'" Campaign finance issues (2022-2023) On September 22, 2022, the North Shore Leader' wrote that Santos' reported net worth had substantially risen between his 2020 and 2022, according to financial disclosures Santos filed as part of his 2020 and 2022 congressional campaigns. In 2020, Devolder-Santos' filed personal finance disclosures that listed no more than $5,000 in assets and a yearly salary of $55,000. Two years later, as part of his 2022 campaign, Devolder-Santos filed financial disclosures that indicated he earned between $3.5 million and $11.5 million from the Devolder Organization, a firm Devolder-Santos founded in 2021. The disclosure also stated Devolder-Santos loaned his congressional campaign more than $700,000. In an interview with Semafor on December 28, Devolder-Santos said the Devolder Organization was in the capital introduction business. Devolder-Santos' said that part of his wealth came from several million-dollar contracts he received within six months of starting the firm. On January 9, 2023, The Campaign Legal Center, a nonprofit group focused on campaign finance, filed a complaint with the Federal Election Commission asking the organization to investigate the source of Devolder-Santos' campaign funds. On January 10, U.S. Reps. Daniel Goldman (D-NY) and Ritchie Torres (D-NY) filed a complaint with the House Ethics Committee asking the body to investigate Santos' financial disclosures. "At a minimum, it is apparent that [Santos] did not file timely disclosure reports for his most recent campaign. Moreover, his own public statements have contradicted some information included in the 2022 financial disclosure and confirmed that the 2022 financial disclosure failed to disclose other required information," the complaint read. In response to the complaint, Santos said, "[Goldman and Torres] are free to do whatever they want to do. ... I have done nothing unethical."

Devolder-Santos' campaign biography said that he had worked as an associate at Citigroup before joining Goldman Sachs. The New York Times reported that there were no records of Devolder-Santos working at those firms. On December 26, 2022, Devolder-Santos said in an interview with the New York Post that he had never been directly employed by Citigroup or Goldman Sachs, but that a company he worked for had been in limited partnerships with the firms. Devolder-Santos said the misunderstanding was due to a "poor choice of words." In 2021, Devolder-Santos said he and his family owned 13 rental properties. In December 2022, Devolder-Santos told The New York Post that claim was not true. “George Santos does not own any properties,” Santos said.