Mark F. Giuliano, a career FBI official who was second-in-command at the law enforcement agency when it launched a controversial investigation into Hillary Clinton’s private email server as she sought the 2016 Democratic nomination for president, died March 2 at his home in Decatur, Ga. He was 62. The cause was an apparent heart attack, said his sister Ann Britz. In an FBI career that began in 1988 and spanned almost three decades, Mr. Giuliano started as a street agent in Washington pursuing violent crime and gangs. He later supervised high-profile criminal cases and the FBI’s Ten Most Wanted program....