One of the Biden family’s closest political and legal advisers whose name shows up in Hunter Biden’s laptop computer is on President-elect Joseph R. Biden’s Justice Department transition team. Alexander S. Mackler, who served as a deputy counsel to Vice President Biden, was a prosecutor in the Delaware U.S. attorney’s office in 2018 about the time the Justice Department opened an inquiry into whether Hunter Biden had cheated on his taxes. Mr. Mackler told The Washington Times that he did not know about the case when he was a federal prosecutor. “I learned about the investigation through Hunter Biden’s press...