As Hillary Clinton closed in on the presidential nomination in the spring of 2016, FBI field officers advised colleagues at headquarters to press her on the foreign donations flowing to the Clinton Foundation while she steered American foreign policy and whether she had used the charity as a campaign piggy bank. But the FBI HQ in Washington — a city in which the former secretary of state and first lady wields enormous influence — let the trail go cold. FBI New York Assistant Director in Charge Diego Rodriguez advised agents in Washington to ask Clinton several questions about the foundation,...