Omar Fekeiki, a 28-year-old Iraqi citizen studying journalism at UC Berkeley, was at his campus apartment when he received news that chilled his heart: His friend and Washington Post colleague Salih Saif Aldin had been murdered while on assignment in a Baghdad neighborhood. Just two weeks before, Aldin, 32, had called Fekeiki to thank him for being a good mentor. "He died for us to get the story,"...