HARRISBURG — Attorney General Kathleen Kane's chief of staff resigned on Friday, four months into the job. Blake Rutherford, who took the position in December, follows others who left key positions under the embattled state prosecutor. Four aides quit last year as a grand jury investigated Kane for allegedly leaking secret grand jury information. She has replaced five spokespeople since 2013, including one who quit in February. Rutherford surprised staffers by emailing a notice that he had resigned. “Today is my last day at OAG. While I will miss working alongside each of you, I am excited about what this...