A month after he declared his intention to run for Congress in 2020, George Santos asked an old lawyer friend to do him a favor. Police in Pennsylvania were seeking him on a theft charge, but it was all a mistake. Could she help clear things up?

She agreed, recalling later that the charge was eventually dismissed and then expunged.

But the circumstances of the case — centering on bad checks and puppies — hew closely to other dubious episodes in Mr. Santos’s history that have surfaced in the months after his election to the House in November. And Mr. Santos’s friend now questions whether she unknowingly enabled him to get away with a crime.

“I should have never got involved,” said the friend, Tiffany Bogosian. “He should have went to jail. And I wish nothing but bad things for him.”

The charge concerned nine checks totaling $15,125 from Mr. Santos’s account, according to an email that Ms. Bogosian sent to the Pennsylvania authorities. On the memo lines of six checks, the purpose was listed as “puppy” or “puppies.” At the time, Mr. Santos was running a group called Friends of Pets United, which he has described as an animal rescue charity.

Mr. Santos was charged after the checks — at least one of which was made out to a dog breeder in Bird-in-Hand, in the heart of Pennsylvania’s Amish Country — bounced, according to Politico, which first reported the case.

Days later, Politico reported, his charity held an adoption event at a Staten Island pet store.

Ms. Bogosian, a lawyer in New York City, agreed to send an email to Pennsylvania State Police. She said in an interview that Mr. Santos told her that his checkbook had been stolen; the case, she said, was eventually expunged.

The revelation that Mr. Santos was charged criminally in 2017 comes as federal investigators are looking into his animal charity. Mr. Santos ran the charity between 2015 and 2018, which he has claimed helped get 2,500 dogs adopted.

Mr. Santos, a Republican representative from Long Island and Queens, also faces criminal and ethics inquiries after it was discovered that he falsified his background and qualifications on the campaign trail. Prosecutors in Brazil have also revived a criminal case against him there that involves check fraud.

Mr. Santos’s lawyer, Joe Murray, declined to comment.

According to Politico, Mr. Santos was charged in York County, Pa., in November 2017 with theft by deception, but the record was expunged in November 2021 — leaving no trace of the case in state or county court records.

Kyle King, a representative for the York County district attorney’s office said that the office had no record of Mr. Santos “in our prosecutorial database,” including under other names he used at times in his personal and professional life.

Mr. King would not say whether the database would contain records of Mr. Santos if his case had been expunged, saying only that the district attorney’s office could not “confirm or deny the existence of any expunged material.”

Ms. Bogosian said that Mr. Santos told her he did not write the checks, and only learned about the charge after he discovered that the police in New York had a warrant for him.

In her email, Ms. Bogosian said that Mr. Santos had been a “victim of fraud,” pointing out that the signatures differed on each of the checks, and that none of them matched the signature on Mr. Santos’s driver’s license.

It is not the first time that Mr. Santos claimed to have been the victim of a robbery: In 2016, court files show, he told a judge in an eviction case that his rent was late because he was mugged on his way to pay it. In a 2022 interview with a Brazilian podcast first reported by the Rachel Maddow Show on MSNBC, he said that he had been robbed in the middle of Fifth Avenue and had the shoes stolen off his feet.

Mr. Santos has also faced scrutiny for how he handled funds raised for Friends of Pets United.

A veteran, Rich Osthoff, has said that he never received $3,000 that Mr. Santos raised on GoFundMe so that Mr. Osthoff’s dog could have lifesaving surgery. A New Jersey farm owner has said Mr. Santos never gave her the proceeds from an event the charity hosted on her behalf.

And even as Mr. Santos told people Friends of Pets United was running a tax-exempt nonprofit, the Internal Revenue Service and officials in New York and New Jersey said he was not registered with them.

The owner of the Staten Island pet store who hosted some of Mr. Santos’s charity adoption events also raised questions about how he handled checks. After one such gathering, at Pet Oasis on Staten Island, Mr. Santos asked the owner, Daniel Avissato, to write a check for donations out to him, according to Mr. Avissato.

Mr. Avissato instead addressed the check to Friends of Pets United but later looked at his bank records and saw that the check had been altered to be made out as Mr. Santos had requested.

Mr. Santos also has a history of writing bad checks, court records show. In 2008, just before his 20th birthday, Mr. Santos spent nearly $700 at a store in Brazil using a stolen checkbook and a false name.

Mr. Santos admitted the fraud to the store’s owner in August 2009 in a social media message. The following year, he and his mother told the authorities that Mr. Santos took the checkbook of a man his mother had been working for, then used it to make fraudulent purchases. Brazilian authorities have said they intend to revive the case against Mr. Santos.