Craig Lang, who is charged with killing a Florida couple in 2018, has become a cause célèbre in the country where he has fought as a mercenary. In the spring of 2015, former U.S. soldier Craig Lang traveled to Ukraine and joined a paramilitary group fighting the Russians. “I never noticed any fear,” said Mamuka Mamulashvili, who commanded Lang in the Georgian Legion. Four years later, Lang is under house arrest in Ukraine. His situation has nothing to do with his conduct inside the eastern European country. Lang is facing charges in the U.S. for allegedly killing a Florida couple...