Rep. George Santos, R-N.Y., has been charged by federal prosecutors in the Eastern District of New York, according to sources familiar with the matter.
The charges are under seal so the nature of the allegations is currently unclear.
The embattled congressman could make his initial appearance in federal court as soon as Wednesday, sources familiar with the matter told ABC News.
MORE: Investigations and complaints facing George Santos could bring serious penaltiesOnly when Santos appears will the criminal charges be unsealed.
As a sitting member of Congress, Santos will likely be afforded the opportunity to turn himself in.
News of the charges was first reported by CNN.
While the charges remain sealed, sources have previously told ABC News that the FBI, federal prosecutors in the Eastern District of New York, and the district attorneys' offices in Queens and Nassau counties have been investigating Santos.
Investigators have been focusing on Santos' financial disclosures, according to sources.
Additionally, as ABC News previously reported, the FBI contacted a Navy veteran, Richard Osthoff, about a GoFundMe campaign Santos established to raise money for the veteran’s service dog.
Santos established the GoFundMe account under the auspices of a charity, Friends of Pets United, and raised $3,000 to help Osthoff pay for surgery to remove a tumor from the dog, sources said.
But Osthoff told ABC News Santos did not come through with the money and ignored text messages about it. The dog, Sapphire, subsequently died.
MORE: Veteran who claimed George Santos stole money for his dying dog says FBI has reached out to himSantos insisted earlier this year he would serve out his term despite mounting controversies surrounding his past falsehoods, scrutiny of his finances, and multiple investigations.
Santos, who has admitted to fabricating parts of his biography, has denied any criminal wrongdoing.