- Now we go to an embattled New York Congressman, George Santos, officially under FBI investigation as agents look into his role into an alleged GoFundMe scheme. Our senior congressional correspondent Rachel Scott has the latest. RACHEL SCOTT: This morning, ABC News learning the FBI is investigating whether George Santos was involved in an animal charity scam. WILL STEAKIN: Are you worried about being prosecuted? GEORGE SANTOS: I have no clue. I don't know what it's about. RACHEL SCOTT: Santos denying any wrongdoing when questioned by ABC News's Will Steakin. - They talk to you more than they talk to me. I haven't been reached out by them. So I can't comment. RACHEL SCOTT: But Navy veteran Richard Osthoff alleges the New York Congressman stole $3,000, money that Santos promised would help his dying service dog. - I don't ever want to see another person, especially a veteran, go through something like this again. RACHEL SCOTT: Osthoff telling us federal authorities contacted him as part of their probe, saying, "I'm glad to get the ball rolling with the bigwigs." He says when his dog, Sapphire, had a tumor, a veterinarian technician referred him to a pet charity run by Santos. But ABC News has reported that charity never existed. Osthoff says Santos suddenly stopped responding to his messages, never turning over a penny. His dog, Sapphire, passed away less than a year later. - I was suicidal again after she went. I needed that dog. RACHEL SCOTT: Santos denied he ever met Osthoff. - He claimed he never met me, and I never met him. That's on the record. RACHEL SCOTT: But a source close to GoFundMe confirmed the account belonged to Santos. Sources say federal prosecutors and the New York attorney general, both investigating Santos, are looking into the charity, along with probes of his campaign finances, even of allegations he stole checks as a teenager in Brazil. With pressure growing on Santos to resign, the Long Island Republican is defiant. - I know that a lot of people want to create this narrative that I faked my way to Congress, which is absolutely categorically false. - GoFundMe declined to comment on any specific details. But a spokesperson tells me that they always cooperate with any ongoing investigations. Santos has already admitted to misrepresenting large parts of his resume and his background. But it's these allegations of deception and theft that could land him in real legal trouble, Linsey. - Yeah, he continues to be dogged by these allegations. Rachel, thank you.