these two men, libyan operatives of some kind, and you hear their names for the first time: abdel basset al-megrahi and lhamen fhimah. >> abdel basset al-megrahi is accused of being the mastermind of the pan am 103 bombing. >> dornstein: i remember the story coming on and trying to feel something about this. "my god, it was libya." and i remember trying to work up a sense of the proper hatred for these two men. >> at that point, my reaction was, "oh, thank goodness, we're going to see two of the murderers brought to justice." >> fhimah allegedly brought plastic explosives from libya to malta, where the two men constructed a bomb. >> dornstein: were you interested in the details: who built the bomb, and where was it made, and how was it transported? did those kind of details interest you? >> they certainly did. i mean, if somebody tells you something, somebody says, "look, megrahi did it," my reaction to that is, "well, prove it." >> dornstein: the plot reportedly came down to a bomb built into a radio cassette player packed with semtex explosive. it was the libyans who were accused of buying the cl

only one person, abdel basset al megrahi, was convicted and sentenced to life, but was released in 2009 because of deteriorating health. >> president obama said the u.s. deeply regrets the decision and warned libya not to give him a hero's welcome. the libyans weren't listening. >> al megrahi emerged wearing a suit, the inmate unrecognizable as he acknowledged the jubilant crowd. >> i remember being shocked by alpb his conviction hadn't been fully satisfying, but at least it was an answer. now all that was coming undone. my brother and the others had been killed, and certainty about who did it was being wiped away. >> some believe al megrahi should go free. they don't believe he was guilty in the first place. >> al megrahi is not expected to live long enough for his next appeal to be heard. >> al megrahi's release also gave momentum to those who believed he wasn't guilty at all, and theories pinning lockerbie on iran were once again revived. i wished i could let it go, but instead i decided to set out on my own search for answers. i began by tracking down the f.b.i. agent who had worked