Robert Mueller III, who led the FBI in the aftermath of the 9/11 attacks—overseeing its rapid modernization as an intelligence and counterterrorism organization—died on March 20 after a yearslong battle with Parkinson’s disease. He was 81. A jut-jawed former Marine and federal prosecutor, Mueller was widely respected across party lines for his fidelity to the rule of law and his patrician dedication to public service. But in the twilight of his career, after he was appointed to be the U.S.