WASHINGTON — President Biden’s lawyers told the Justice Department in November that they had no reason to believe that copies of official records from his vice presidency had ended up anywhere beyond a think tank in Washington, where several classified documents had been found that month, two people familiar with the matter said on Sunday.
That assertion, the people said, was based on interviews with former officials who had been involved in the process of packing and shipping such material. The Biden legal team had surveyed them after the discovery on Nov. 2 of a small number of classified files in a closet of his former office at the Penn Biden Center, seeking to understand how the files got there.
But it would turn out that a handful of classified records were at Mr. Biden’s residence in Wilmington, Del., too. The mistaken premise, according to the people, who spoke on the condition of anonymity to discuss the sensitive matter, helps explain why roughly seven weeks elapsed before Mr. Biden’s lawyers searched boxes in the garage at his Wilmington home on Dec. 20 and found several more classified papers.
The escalating scrutiny Mr. Biden faced over his handling of the materials in turn led to the discovery of yet more sensitive documents at his residence this month, when Attorney General Merrick B. Garland also appointed a special counsel. And on Friday, F.B.I. agents — at the invitation of Mr. Biden’s lawyers — conducted an extraordinary search of every room in his Wilmington home, finding another half-dozen files marked as classified dating back to his time as a senator.
The account by the people familiar with the matter shed new light on a sequence of events that has led to significant political turbulence for Mr. Biden. It comes as former President Donald J. Trump is also under investigation by a special counsel over his repeated refusal to return sensitive documents after he left the White House, including his failure to comply with a subpoena that prompted the F.B.I. to get a warrant to search his Florida residence.
Understand the Biden Documents Case
The discovery at two locations of classified documents from President Biden’s time as vice president has prompted the Justice Department to scrutinize the situation.
Former officials familiar with the packing up of Mr. Biden’s office in the White House and the vice president’s Naval Observatory home at the end of the Obama administration had told Mr. Biden’s lawyers that there were two primary sets of materials, the people said.
One set was believed to be material that might be useful to Mr. Biden for his post-vice-presidential career in public life or teaching, like his speeches and unclassified policy memos about topics he was interested in. Those materials were initially shipped to two transition offices and then on to his office at the Penn Biden Center when it opened in 2018. (The National Archives and Records Administration would keep original copies of the official records.)
The other set, the people said, was believed to contain no official records. It was supposed to be material like political campaign-related documents and old campaign memorabilia, which are exceptions to what counts as presidential records. Those boxes were shipped to the garage of his Wilmington residence, the people said.
Mr. Biden’s personal lawyers, led by Bob Bauer, told the Justice Department they had no basis to believe official records had gone anywhere but the Penn Biden Center after it notified them on Nov. 10 that it was scrutinizing the classified files. The lawyers stopped conducting their own review of how the documents could have gotten there and told the department what steps they had taken up to that point, the people said.
The Biden legal team also said they would inform the Justice Department if any government records from his vice presidency were later located elsewhere or they learned a reason to believe such files might be in another location. Soon after, Mr. Garland assigned John R. Lausch, a U.S. attorney in Chicago who had been appointed by Mr. Trump, to determine whether a special counsel should be installed.
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Mr. Biden’s lawyers initially hoped the Justice Department’s preliminary inquiry would be brief. But as weeks passed, they decided as a matter of due diligence — and not because of any new information — that it made sense to check the boxes in the garage, too, the people said; the lawyers did not inform the Justice Department ahead of time.
On Dec. 20, once they found several classified records in those boxes, they notified the Justice Department, which prompted discussions about whether any further such files might be in the main residence.
Against that backdrop, Mr. Biden’s personal lawyers decided they would search several work and storage areas inside the living area of the house, the people said; this time, they told the Justice Department of the plan and said they would let the government know of the results.
After finding a classified page in one of those rooms on Jan. 11, they stopped searching and alerted the Justice Department. When law enforcement officials came to retrieve that page, five more classified pages were discovered in the same area.
Everyone involved understood and agreed that the discovery of those six pages meant that the government would have to conduct its own search of the work and storage areas in the house that the Biden legal team had identified, the people said. But the Biden legal team invited the F.B.I. to also search every room in the residence — including bathrooms, bedrooms and the utility room, the people said.
The rationale, the people said, was that an independent search by the F.B.I. would allow a swift and definitive determination of whether any more classified files were inappropriately stored at the house.
House Republicans, now in the majority, have vowed to press forward with their own investigation. On Sunday, Representative Michael R. Turner, an Ohio Republican who is likely to oversee the House Intelligence Committee, accused Mr. Biden of being a “serial classified document hoarder” and suggested that he must have been showing the documents to people.
“This is going to be crucial, I think, to the special counsel’s investigation, is why did the president have these documents?” Mr. Turner said on CBS’s “Face the Nation.” “Who did he show them to? And is it connected to the Biden family businesses?”
Even as Senator Richard J. Durbin of Illinois stressed that Mr. Biden and Mr. Trump had responded very differently to the discovery of classified material after they left office, he was also critical, calling the situation “outrageous” on CNN’s “State of the Union.”
It has diminished Mr. Biden’s stature even if it turns out to have been the fault of an aide because “the elected official bears ultimate responsibility,” Mr. Durbin said.