Federal prosecutors signaled Friday that former national security adviser John Bolton may face additional criminal charges as the Justice Department continues sifting through a vast collection of materials seized from his Maryland home and Washington office.

At a hearing in Greenbelt, Maryland, Assistant U.S. Attorney Thomas Sullivan told U.S. District Judge Theodore Chuang that the government is still reviewing classified information it alleges Bolton unlawfully shared during President Donald Trump’s first term. The intelligence community must first examine the seized material before any of it can be shown to Bolton’s defense team, a process prosecutors say is complicated by a filter team looking through it for possible attorney-client privilege problems.