The White House on Thursday said it is confident that an investigation into the discovery of classified documents will find that President Biden accidentally misplaced them.

“We are confident that a thorough review will show that these documents were inadvertently misplaced, and the President and his lawyers acted promptly upon discovery of this mistake,” Richard Sauber, special counsel to the president, said in a statement.

Sauber added that the White House has “cooperated closely with the Justice Department throughout its review, and we will continue that cooperation with the Special Counsel.”

The statement comes after Attorney General Merrick Garland announced earlier Thursday that he would appoint Robert Hur as special counsel to investigate the discovery of classified documents at an office once belonging to Biden and at his Wilmington home. Hur, a Trump appointee who served as the U.S. attorney in Maryland, will return to the department to conduct the investigation.

Officials said a first batch of documents were first discovered in early November at a Washington office Biden used after the Obama administration, with Biden attorneys notifying the National Archives and the Justice Department of the matter on Nov. 4. The public has only been aware of the matter since Monday following reporting from CBS News.

A second batch of classified documents were found in a storage space in the garage of Biden’s Wilmington, Del., residence and another one-page document was discovered among stored materials in an adjacent room, the White House confirmed Thursday morning following a report the day before by NBC News.

Biden earlier on Thursday acknowledged the second batch of documents were discovered and said they were in a garage that was locked, along with his corvette. He also reiterated that he takes “classified documents and classified material seriously.”