Here's one reason why Trump requested a 'special master'

Trump
The US government faces a deadline today to respond in writing to former President Donald Trump's request for a special master to oversee the FBI's review of evidence seized at his Mar-a-Lago residence. A special master is a third-party attorney appointed by a court to oversee part of a certain case. A federal judge has signaled a "preliminary intent" to grant the request, which could bring new complications to the DOJ's closely watched investigation into the White House documents Trump took to Mar-a-Lago. If appointed in Trump's case, the special master would oversee the Justice Department's review of the evidence gathered from his private club and filter out privileged material that may have been seized in the search.