The chairman of one of two House committees on which George Santos will sit has defended the decision, despite the New York Republican’s résumé having been shown to be largely made up, and amid allegations of deceitful and criminal behaviour now including bilking a disabled veteran out of $3,000 raised to save the life of his dog, and fabricating a story about his mother surviving the 9/11 attacks.

The disabled veteran, Richard Osthoff, told the news site Patch he was “crying his eyes out remembering Sapphire’s last day”.

In Congress, however, Roger Williams of Texas, the chair of the small business committee, told CNN of Santos: “I don’t condone what he said, what he’s done. I don’t think anybody does. But that’s not my role. He was elected.”

Santos will also sit on the science, space and technology committee. CNN said requests for seats on panels dealing with the financial sector and foreign policy were rebuffed.

Santos won election in New York’s third district in November. Since then, he has been the subject of relentless media scrutiny, calls to resign from his own party and from Democrats, and multiple calls for investigations of his campaign finances.

But Williams was following a party line set by the new House speaker, Kevin McCarthy, who Santos supported through 15 votes for the speakership and who must work with a narrow majority.

House Democrats led by Daniel Goldman and Ritchie Torres, both from New York, have called for an investigation of what Republican leaders knew about Santos’s deceptions before he won election and was seated.

On Monday, McCarthy told reporters: “I never knew about his résumé or not, but I always had a few questions about it.”

On Tuesday, Goldman said: “The public has no choice but to believe that McCarthy was complicit in concealing Mr Santos’s lies in order to flip a seat in a win-at-all-costs effort to gain power.”

Amid spiraling claims about Santos’s personal and professional life, it was alleged on Tuesday that he stole $3,000 from a fundraising account set up to pay for life-saving surgery for Osthoff’s dog.

According to Patch, Santos became involved with Osthoff and his dog, Sapphire, in 2016.

Needing to raise money, the report said, Osthoff was told that a man named Anthony Devolder, with a pet charity called Friends of Pets United, could help.

As Patch reported, “Anthony Devolder is one of the names Long Island representative George Santos used for years before entering politics in 2020.”

Osthoff, who provided text message exchanges he said he had with Devolder, said Santos eventually took the money and disappeared. Osthoff’s dog died.

“Little girl never left my side in 10 years,” Osthoff said. “I went through two bouts of seriously considering suicide, but thinking about leaving her without me saved my life. I loved that dog so much, I inhaled her last breaths when I had her euthanised.”

Santos did not comment to Patch but did deny the allegation in a message to the news outlet Semafor.

“Fake,” Semafor quoted Santos as saying, in a text. “No clue who this is.”

Yet another of Santos’ fibs came to light later on Wednesday, when the Washington Post reported that the congressman’s story about his mother surviving the World Trade Center attack during 9/11 did not align with immigration records that said she was not in the US at the time.

For now, Santos continues to find his feet in Congress. According to the New York Times, he is showing signs of aligning himself with far-right pro-Trump representatives including Matt Gaetz of Florida and Marjorie Taylor Greene of Georgia.

Santos has not answered many questions from reporters. In rare comments, he has admitted “embellishing” his résumé but denied wrongdoing and said he will not resign.