In less than two hours, he will appear in a federal courtroom in Washington to face charges for the attack that killed 270 people on board and on the ground in Lockerbie, Scotland.

Nick Robertson has long followed this tragedy, and he joins me now.

Nick, what does this mean?

Um, this means that the families may get closer to justice.

This means they may get more details about how and why the bomb was placed, we know that this agent has already confessed to setting the timer on the bomb to 11 hours, to being congratulated at the time for the successful mission in bringing down Pan Am 103, congratulated by the Libyan dictator Muammar Gaddafi.

So there is an opportunity here for a lot more discovery.

Almost 34 years since the deadliest terror attack in British history, and the man accused of building the bomb that killed 270 people, mostly Americans, is finally going to face justice in a US court.

A huge moment for victims families.

This has been one of our, it has been the top priority to find the truth and hold these people accountable.

And the fact that this is now going to happen in the US is, it's, it's monumental.

Libyan Abu Agila Muhammad Masud Khair Al-Marimi was arrested for his alleged role in blowing up Pan Am Flight 103 over Lockerbie, Scotland.

38 minutes after it took off for the US from London.

Killing everyone on board and 11 people on the ground.

The US first charged Al-Marimi for his involvement in the attack two years ago, while he was already in custody in Libya for unrelated crimes.

It is alleged in the criminal complaint and the indictment that at that time, all co-conspirators worked together to arm the explosive device in the suitcase.

For years, the only person convicted in the Lockerbie bombing case was Abdul Basset Al-Megrahi.

Al-Megrahi, a former Libyan intelligence official, was accused along with another Libyan man, who was acquitted.

For planting the explosive inside a portable cassette player in a suitcase on the plane.

Al-Megrahi was sentenced to life in prison, but eight years after his conviction in 2008, he was released from a Scottish prison with terminal prostate cancer.

Arriving home in Libya, he received a hero's welcome.

In 2011, following the revolution that toppled Libya's dictator Muammar Gaddafi.

I visited Al-Megrahi at his home in Tripoli.

He was near death, his family, as they always had, protesting his innocence.

Has he been able to see a doctor?

No, there is no doctor and there is nobody to ask and we don't have any phone line to call anybody.

What's his situation right now? He stop eating and he sometimes is come in coma.

Coma.

He goes unconscious.

Yes.

He died the following year without ever proving his innocence.

Al-Marimi's trial will likely revisit part of Megrahi's defense, particularly alleged inconsistencies about how the bomb came to be on the plane.

Now, Al-Marimi has also known as Masoud in the court documents has a lot of evidence stacking up against him.

One of the questions for the court is this testimony that was taken from him by a Libyan law enforcement agent 10 years ago, is that going to be admissible in court?

That's a question mark.

What is unchangeable and what is fact in evidence is Masoud's fingerprints are on a ticket stub that placed them at the scene when the bomb was put on that aircraft.

This is damning evidence.