Aides to former Vice President Mike Pence found a small number of documents with classified markings at his home in Indiana during a search last week, according to an adviser to Mr. Pence.
The documents were “inadvertently boxed and transported” to Mr. Pence’s home at the end of President Donald J. Trump’s administration, Greg Jacob, Mr. Pence’s representative for dealing with records related to the presidency, wrote in a letter to the National Archives.
The letter, dated Jan. 18, 2023, said that the former vice president was unaware of the existence of the documents and reiterated that he took seriously the handling of classified materials and wanted to help.
Mr. Jacob wrote that Mr. Pence hired an outside lawyer after classified documents were found in recent days at the residence and former private office of President Biden. Mr. Jacob also said the lawyer could not specify anything more about the documents because the lawyer had stopped looking once it was clear the documents had classified markings.
The disclosure adds more questions about how classified material is handled at the top levels of government at a moment when Mr. Biden and Mr. Trump are both subjects of special counsel investigations on the matter.
Mr. Trump has been under federal investigation for nearly a year for how hundreds of documents with classified markings, as well as hundreds of pages of presidential records, wound up at his private club and residence, Mar-a-Lago.
Mr. Trump resisted the urging of aides to give boxes of documents with unknown contents to the National Archives. When he eventually turned over 15 boxes, archives officials found hundreds of pages with classified markings. Mr. Trump later faced a grand jury subpoena to turn over any remaining documents, and one of his lawyers wrote a statement saying everything had been turned over. When investigators found evidence that was not the case, the F.B.I. searched his club in August.
Mr. Biden, by contrast, has cooperated since the discovery of documents at his nonprofit offices and then his home. Mr. Jacob, who was Mr. Pence’s general counsel while he was vice president, stressed cooperation in the letter to the National Archives.
Still, aides to Mr. Pence had previously said they were confident that the vice president had not retained any classified documents after he left office.