A State Department staffer who oversaw security and technology issues for Hillary Clinton is refusing to answer Senate investigators’ questions about the former secretary of state’s use of a private email server — marking the second time an ex-State employee has declined to talk to lawmakers. John Bentel, a now-retired State employee who managed IT security issues for the top echelon at the department, declined to be interviewed by GOP staff on the Senate Judiciary and Homeland Security committees, according to a letter obtained by POLITICO. The chairmen of both committees, Sens. Chuck Grassley (R-Iowa) and Ron Johnson (R-Wis.), are...