Destruction and scorched crater in a residential section of Locerbie.
(Photo: Martin Cleaver/AP)

270 people died when Pan Am 103 was blown out of the sky over Lockerbie, Scotland on December 21, 1988. It was the worst-ever act of airline terrorism against the United States. It's also been called the world's biggest unsolved murder.

Finally, after 11 years of investigation, political stalemate, and legal delays, two Libyan men prepare to face trial for the Lockerbie bombing starting May 3, 2000, in the Netherlands.

But many observers - including legal and law enforcement officials close to the case - say the trial may not produce a satisfying answer to the question of who bombed Pan Am 103.

In this special report, journalists Ian Ferguson and John Biewen of American RadioWorks explore the case against the Libyans - its strengths and weaknesses.

They also examine the evidence against other suspects, most notably the Iranian government and a terrorist group based in Syria. Some experts, and people who lost loves ones on Pan Am 103, question whether the most likely culprits are going on trial.

View of Lockerbie, 1999.
(larger view)

Pan Am 103 climbed into the dark English sky at 6:25 in the evening on December 21, 1988. It headed northwest from London's Heathrow Airport toward Scotland and the North Sea and, ultimately, scheduled destinations in New York and Detroit. The Jumbo Jet carried 259 passengers and crew. The majority were Americans, many of them returning for holiday gatherings with family and friends. But just 38 minutes into the flight, as the 747 cruised at 31,000 feet over the border from England into Scotland, something in the cargo hold exploded. It blew a hole the size of a large dinner plate in the airliner's skin. The loss of air pressure caused a powerful rush that broke the plane to pieces. Six miles below, in the Scottish border town of Lockerbie, a woman looked up at the sky.

"There was this absolutely massive sort of red glow in the sky that went firstly upwards and then out," the woman told a TV interviewer later that night. "We thought it was some sort of, like, nuclear explosion."

But then things began to fall like violent rain from some nightmare: airplane parts, suitcases and their contents, packages gift-wrapped for the holidays. Tons and tons of aviation fuel. And people.

In one Lockerbie neighborhood, a 60-foot section of fuselage, with 60 bodies inside, landed between two rows of houses, miraculously missing them all. Across town a jet engine the size of a small truck landed like a small meteor in the parking lot of an apartment building, leaving a crater but injuring no one. Bodies rained on a golf course. Amid the near-misses, one tragic strike: a wing of the 747 fell directly on three houses, creating a fireball that burned so hot it vaporized the homes and the eleven people inside them.