A computer specialist who deleted Hillary Clinton’s emails despite orders from Congress to preserve them was given immunity by the Justice Department during its investigation into her personal email account, according to a law enforcement official and others briefed on the investigation. Republicans have called for the department to investigate the deletions, but the immunity deal with the specialist, Paul Combetta, makes it unlikely that the request will go far. Representative Jason Chaffetz of Utah, the top Republican on the House oversight committee, asked the Justice Department on Tuesday to investigate whether Mrs. Clinton, her lawyers or the specialist obstructed...