The Justice Department is asking a federal judge to hold Donald Trump in contempt of court for failing to comply with a subpoena issued this summer ordering the former president to turn over records marked classified, two sources familiar with the matter told CNN.The development comes after Trump's legal team said it conducted searches at four locations just before Thanksgiving, finding two documents with classified markings at a storage facility in Florida. The Trump team turned over those two documents to the FBI and announced to a federal judge in Washington, D.C., that they believed Trump was now in compliance with a 6-month-old subpoena.But the Justice Department disagreed. And in an escalation last week, department prosecutors told DC District Chief Judge Beryl Howell, who oversees federal grand jury proceedings there, that the searches weren't satisfactory. The contempt proceedings before Howell are under seal.The proceedings ratchet up the pressure on Trump as he faces possible criminal liability in the Mar-a-Lago documents investigation being conducted by special counsel Jack Smith. It also adds another chapter to the ongoing struggle for federal officials to reclaim government records — especially those that contain national security secrets — from Trump after his administration ended.In January and June, the Trump team turned over boxes and an envelope of federal records, including some marked as classified. Federal agencies had been seeking their return for months, and the Justice Department issued a subpoena that asked for documents marked as classified in May.Even after the subpoena, investigators found reason to search Mar-a-Lago, seizing 33 more boxes of records, including more than 100 documents marked classified. More recently, prosecutors have insisted that sensitive government documents are still missing and that Trump was obligated to return them.The Justice Department has not disclosed to Trump's legal team which materials it believes have not been returned, according to one source.A hearing is set for Friday, when Howell will consider whether to hold Trump and his post-presidency office in contempt of court. If held in contempt, he could rack up fines. Being held in contempt over subpoenas for documents has become a feature of Trump's court tangles since he left office.