The White House is working with the Justice Department as it reviews classified documents from when President Biden served as vice president that were found in a private office last fall.

Attorneys for Biden discovered the documents in November and notified the National Archives, Richard Sauber, special counsel to Biden, said in a statement. The Archives took possession of the materials the following morning and has since referred the matter to the Justice Department for further investigation.

“The White House is cooperating with the National Archives and the Department of Justice regarding the discovery of what appear to be Obama-Biden Administration records, including a small number of documents with classified markings,” Sauber said.

The materials were first discovered at an office at the University of Pennsylvania in Washington while it was being cleaned out, Sauber said. Biden had used the office while he served as an honorary professor for the university from 2017 to 2019.

“The documents were not the subject of any previous request or inquiry by the Archives,” Sauber added. “Since that discovery, the President’s personal attorneys have cooperated with the Archives and the Department of Justice in a process to ensure that any Obama-Biden Administration records are appropriately in the possession of the Archives.”

The discovery of the documents was first reported by CBS News. The president and vice president are required under the Presidential Records Act to turn over documents to the National Archives for secure storage.

That classified documents from Biden’s time as vice president were not in possession of the National Archives is sure to ignite criticism from conservatives given former President Trump is under investigation for allegedly taking numerous classified government documents to his Mar-a-Lago estate in Florida upon leaving the White House in 2021. During an unprecedented FBI search of the property, more than 100 documents were obtained that federal officials said were marked with varying degrees of classification. 

In response to the news involving Biden, Donald Trump Jr. tweeted, “When will the FBI’s Hostage Rescue Team storm one of Biden’s many vacation homes bought and paid for somehow by a lifetime of being a humble public servant?” 

But one key difference was that Biden’s team quickly alerted the National Archives upon discovering the documents, while Trump was still in possession of his files until an FBI search in August.

“Attorneys for President Biden appear to have taken immediate and proper action to notify the National Archives about their discovery of a small handful of classified documents found in a locked cabinet at the Penn Biden Center so they could be returned to federal government custody,” Rep. Jamie Raskin (Md.), ranking Democrat on the House Oversight and Reform Committee, said in a statement Monday evening.

Matthew Miller, a former Justice Department spokesperson during the Obama administration, tweeted, “Worth noting what former government officials have said since Mar a Lago raid: classified docs get mistakenly removed from government facilities fairly frequently. You report it, turn in the docs, the government does a damage assessment, and that is the end of it.”

“OR…you cover it up, lie about it repeatedly to the government, and force them to raid your premises to retrieve the docs (ie act like a sociopath), in which case you can expect a criminal charge,” Miller added.

—Updated at 8:58 p.m.