Former President Donald Trump’s legal defense team and federal prosecutors appeared at a sealed hearing on Thursday that was related at least in part to the Justice Department’s ongoing demands to make sure all documents marked classified have been returned to the federal government, CNN has learned. This was the first appearance in a DC federal courthouse by the Trump legal team that is primarily handling the Mar-a-Lago documents investigation. The full scope of the two-hour hearing with Chief Judge Beryl Howell is unclear. CNN spotted the lawyers – including James Trusty, Evan Corcoran and Lindsey Halligan for Trump, and prosecutor Julie Edelstein and several others from the Justice Department who are known to be on the case – heading into a sealed proceeding before Howell. The development is the latest sign of prosecutors attempting to move their investigation forward into the handling of documents from the Trump presidency after he left office. Trump’s lawyers declined to tell reporters on the scene why they were at the courthouse. Though Trump’s challenges to the search and seizure of Mar-a-Lago in August have been before judges in Florida, a federal grand jury in Washington, DC, appears to be handling the criminal investigation into obstruction of justice and mishandling of records, including national security secrets. Close Trump adviser Kash Patel, who is designated to work with his records post-presidency, previously appeared before this grand jury two weeks ago and took the Fifth Amendment, declining to answer questions, another sign of prosecutors continuing to build their case, CNN reported. In addition, the Justice Department has been demanding that all sensitive records that might still be in Trump’s possession be returned to the federal government. At least some of that battle to secure the return of any more documents is part of an under-seal court proceeding, CNN previously reported. Howell, of the US District Court in DC, typically handles disputes that arise related to grand jury proceedings, which are kept secret. This story has been updated with additional developments.