When Syed Farook and Tashfeen Malik massacred 14 people in San Bernardino, California in 2015, newly retired Department of Homeland Security Officer Philip Haney was horrified to discover that a major case he spent years developing might have helped prevent the attack had it not been shut down by a branch of his own agency and Hillary Clinton’s State Department. Now, in his ongoing effort to help prevent future attacks by uncovering how the government quashed his case, three federal agencies either have flatly denied they have any communications or records related to the case, known as the Tablighi Jamaat Initiative, or...