It was just a scrap of debris, a battered shard of brown plastic with a few markings on it—but to international investigators on the trail of a killer, it told a gruesome story. In the months after a terrorist bomb blew up Pan Am Flight 103 over Lockerbie, Scotland, in December 1988—killing 259 people, including 189 Americans—U.S. and European investigators scoured the world looking for the culprits. Full Story