• FBI agents found more classified documents at President Joe Biden's home in Wilmington, Delaware, during a consensual search lasting nearly 13 hours.
• Other classified documents were found there earlier this month, and in November at a Washington think tank where Biden kept a private office before becoming president.
• Attorney General Merrick Garland earlier this month appointed a special counsel to investigate Biden's retention of government records after he was vice president.
• Ex-President Donald Trump is under criminal investigation by another special counsel for taking hundreds of classified records from the White House when he left office.

The FBI found more classified documents at the Wilmington, Delaware, home of President Joe Biden during a consensual search Friday that lasted nearly 13 hours, his personal lawyer and a prosecutor said Saturday evening

The discovery was the fourth time since November that classified records or material has been found at a private address of Biden's.

His personal lawyer Bob Bauer, in a statement, said the Department of Justice seized "six items consisting of documents with classification markings and surrounding material."

Joseph D. Fitzpatrick, assistant U.S. Attorney for the Northern District of Illinois, told NBC News: "I can confirm that the FBI on Friday executed a planned, consensual search of the President's residence in Wilmington, Delaware."

Some of the items dated from Biden's tenure in the Senate, where he represented Delaware from 1973 to 2009, Bauer said. And some of the items were from his tenure as vice president in the Obama administration, from 2009 through 2017.

In addition to those records, FBI agents, who did not have a warrant for the search, also seized some notes that Biden wrote by hand as vice president, according to the lawyer and the White House.

Neither Biden nor first lady Jill Biden was present during the search, according to Richard Sauber, special counsel to the president.

The items join other an undisclosed number of classified government records previously discovered by lawyers for the president.

A small number of classified records first were found by Biden's lawyers on Nov. 2 at a private office that he kept at a Washington, D.C., think tank after ending his tenure as vice president in the Obama administration in 2017.

The White House only disclosed that discovery on Jan. 9.

On Dec. 20, a small number of classified records were found in the garage of Biden's Wilmington home.

A single page of classified material was then found at the Wilmington residence on Jan 11. Then, the next day, five more pages of classified records were found in a room adjacent to Biden's garage, when DOJ officials traveled there to take possession of the single page found the prior day.

The White House has said that when the president's lawyers found the previous documents, they immediately notified the National Archives and Records Administration and the DOJ.

Friday's search was the first time revealed publicly that federal law enforcement authorities have conducted a search for government documents at Biden's private addresses.

Attorney General Merrick Garland earlier this month appointed a special counsel to investigate Biden's retention of government records after he was vice president.

Former President Donald Trump is under criminal investigation by another special counsel for taking hundreds of classified records and other government documents from the White House when he left office. Trump is also being eyed for possible obstruction of justice by stonewalling efforts by government officials to recover those documents.

The FBI in early August raided Trump's home at his Mar-a-Lago club in Palm Beach, Florida, where they found thousands of pages of government records. The FBI had a search warrant in that case.

By law, presidents and vice presidents must return government documents to the National Archives when they leave office.

Biden and the White House have been criticized for the two-month lag in disclosing the discovery of the first batch of classified documents at the Penn Biden Center for Diplomacy and Global Engagement in Washington.

That first discovery came six days before the midterm elections when the balance of political party control of both chambers of Congress was a stake.

And critics have asked why searches of other private locations maintained by the president were not conducted until after the White House disclosed the first discovery.

Bauer, in his statement Saturday said that the president's legal team offered to provide "prompt access" to Biden's private residence "to allow DOJ to conduct a search of the entire premises for potential vice-presidential records and potential classified material."

He said that the offer was made "in the interest of moving the process forward as expeditiously as possible."

"DOJ requested that the search not be made public in advance, in accordance with its standard procedures, and we agreed to cooperate," Bauer said.

He said that on Friday, the "DOJ completed a thorough search of all the materials in the President's Wilmington home."

"It began at approximately 9:45 AM and concluded at around 10:30 PM and covered all working, living and storage spaces in the home," Bauer said. "By agreement with DOJ, representatives of both the personal legal team and the White House Counsel's Office were present."

Authorities had "full access to the President's home," which included "personally handwritten notes, files, papers, binders, memorabilia, to-do lists, schedules, and reminders going back decades."

"DOJ took possession of materials it deemed within the scope of its inquiry, including six items consisting of documents with classification markings and surrounding materials, some of which were from the President's service in the Senate and some of which were from his tenure as Vice President," Bauer said.

"DOJ also took for further review personally handwritten notes from the vice-presidential years."

The lawyer said, "As noted in the Statement we released on January 14, we have attempted to balance the importance of public transparency where appropriate with the established norms and limitations necessary to protect the investigation's integrity."

"We will continue to do so throughout the course of our cooperation with DOJ," Bauer said.

Sauber, Biden's White House lawyer, in his own statement, said, "The President and his team are working swiftly to ensure DOJ and the Special Counsel have what they need to conduct a thorough review."

"Since the beginning, the President has been committed to handling this responsibly because he takes this seriously," Sauber said.