A former Watergate prosecutor on Monday urged the federal judge presiding over the prosecution of New York City Mayor Eric Adams to assign a special counsel to help decide how to handle the Justice Department’s request to drop charges. Attorney Nathaniel Akerman told Judge Dale E. Ho in a letter filed in the case record in Manhattan federal court that he sought to intervene because nobody was representing the public’s interest after three attorneys from the Justice Department in Washington made the request Friday. Finally, the judge might appoint an independent special prosecutor to continue the case with access to grand jury materials and other evidence, Akerman said.