BENGHAZI, Libya - A Chinese construction engineer has been killed by unidentified gunmen in Libya’s restive second city Benghazi, medical and security sources said on Wednesday. The 49-year-old was shot dead on Tuesday just four days after an offensive led by a former rebel commander to purge the eastern city of militia left 79 people dead. “Unidentified gunmen forced two other Chinese construction workers to show them the office of the site foreman and then went in and shot him several times,” a security source said.“The other two Chinese staff were later released,” the source said, adding that he had no word on the identity or motive of the killers.