A special counsel investigating President Joe Biden used part of his report to Congress to explain why Donald Trump should be prosecuted for mishandling classified documents.

In declining to prosecute Biden, Special counsel Robert Hur told Congress that the president had willfully retained classified documents, according to NBC News. But Hur said he was declining to charge Biden because of "clear" differences with Trump's classified documents case.

Hur observed that unlike "the evidence involving Mr. Biden, the allegations set forth in the indictment of Mr. Trump, if proven, would present serious aggravating facts."

"After being given multiple chances to return classified documents and avoid prosecution, Mr. Trump allegedly did the opposite," Hur wrote before comparing it to Biden's case.

"Mr. Biden turned in classified documents to the National Archives and the Department of Justice, consented to the search of multiple locations including his homes, sat for a voluntary interview, and in other ways cooperated with the investigation."