Just months after taking office, embattled Republican Rep. George Santos of New York has been charged with at least one federal offense, a source familiar with the investigation told NPR.
Details of the charges, first reported by CNN, aren't yet public.
The federal investigation into Santos' behavior has been handled by the Eastern District of New York in Brooklyn.
Before winning office as a freshman last November, Santos lied about his professional accomplishments, his education and his family's history.
Once the deceptions were made public, Santos faced growing controversy and calls for his resignation.
Critics have also questioned how he raised and spent hundreds of thousands of dollars for his political campaign.
Phone calls to Santos' congressional offices and to his attorney went unanswered Tuesday evening. Santos also hasn't commented on Twitter.
Speaking to reporters at the White House on Tuesday, House Speaker Kevin McCarthy, R-Calif., declined to say whether he would move to push Santos from office.
"I'll look at the charges," McCarthy said.
Santos, who represents communities on Long Island and in Queens, previously gave up all committee assignments because of the scandals he faces.
Santos, who has previously admitted to "embellishing" his resume, has repeatedly denied any criminal wrongdoing.
Separate probes are also underway by the Nassau County district attorney in New York and the House Ethics Committee in Washington, D.C.
A statement released by the House panel in April stated an investigative subcommittee will examine whether Santos "engaged in unlawful activity" during his 2022 campaign.
The Nassau County Republican Committee, which helped elect Santos, has since called on him to resign, as have some prominent GOP lawmakers from New York.
"Close to 80% of people polled think he should not be in office," Rep. Anthony D'Esposito, R-N.Y., told NPR in February, after urging Santos to step aside.
"It's been an absolute distraction at a time when we should be rolling up our sleeves and getting to work," D'Esposito said.
NPR White House Correspondent Tamara Keith contributed to this report.