The initial batch of documents retrieved by the National Archives from former President Donald J. Trump in January included more than 150 marked as classified, a number that ignited intense concern at the Justice Department and helped trigger the criminal investigation that led F.B.I. agents to swoop into Mar-a-Lago this month seeking to recover more, multiple people briefed on the matter said.In total, the government has recovered more than 300 documents with classified markings from Mr. Trump since he left office, the people said: that first batch of documents returned in January, another set provided by Mr. Trump’s aides to...