(NewsNation) — In an unprecedented move, the FBI conducted a search of former President Donald Trump’s Mar-a-Lago residence Monday in connection to a probe of whether Trump mishandled classified documents.

Attorney General Merrick Garland signed off on the search, which lasted more than nine hours, sources confirmed to NewsNation. The Department of Justice has been investigating how boxes of White House records, some of them classified, ended up at Mar-a-Lago after Trump left office.

Former prosecutors Renato Mariotti and Jay Town explained Monday on “Dan Abrams Live” that for the department to make such an unprecedented and public move, there’s likely “plus” factors that go beyond just simply improperly handling classified documents.