Ahmad I. al-Halabi liked to fiddle with robots in high school. He lived in one of the nation's biggest Arab-American communities, and went straight into the Air Force after graduation. He planned to marry his fiancee days after his tour as an Arabic translator ended on Guantanamo Bay. But now al-Halabi, a senior airman — once honored as "Airman of the Year" — is in custody at an Air Force base in California, facing allegations of espionage that could bring the death penalty for the 24-year-old son of Syrian immigrants. The supply clerk-turned-translator is the second member of the U.S....