Lockerbie bombing: Ex-US prosecutor Bill Barr says Abu Agila Masud should face death penalty

William Barr was the US attorney general who announced the charges against Abu Agila Masud two years ago, on the 32nd anniversary of the Lockerbie bombing - the deadliest terror attack ever on UK soil.

He also announced the charges against Abdelbaset al-Megrahi and Al Amin Khalifa Fhimah in 1991 - the only people so far to have been prosecuted over it.

He spoke to BBC News as Mr Masud, who is accused of making the bomb which destroyed Pan Am flight 103, finally appeared in a US court on Monday.

Mr Barr told me the arrest sends an important message that no matter how much time has elapsed, anyone attacking the US will eventually be brought to justice.

He said he had wanted the first Lockerbie trial - which took place in a Scottish court convened in the Netherlands in 2000 - to be held in America. The historic court case saw Megrahi found guilty of murder in 2001, and his co-accused, Al Amin Khalifa Fhimah, found not guilty.

"I wanted it to be tried in the United States as well. And I wanted to pursue the death penalty in the United States," Mr Barr said, at the same moment that Mr Masud was appearing in a courthouse in Washington DC. "I didn't want to proceed to Scotland, partly because Scotland would not impose the death penalty."

"Personally, I think terrorists who commit these kinds of atrocities should be executed," Mr Barr told me.

The prosecution said on Monday that they will not seek the death penalty if Mr Masud is convicted, however.

The US alleges that Abu Agila Masud was a Libyan intelligence operative and played a key role in the 1988 Lockerbie attack.

The case against Mr Masud will include a confession he allegedly gave to a Libyan law enforcement official when he was in custody in Libya on other charges. He is said to have described his role in the attack which included making the bomb, transporting it to Malta and prepping it before it was put into a suitcase and loaded onto a plane.

Mr Barr said he is satisfied that confession will be admissible in court, despite concerns by some that it may have been coerced in the chaotic months following the regime's fall, when Libya did not have a fully functioning legal system.

He added that there is other evidence against Mr Masud, including travel records that show he flew to Malta at the time when the bomb was placed on the plane.

It has not been made public how, where or when Mr Masud was arrested by the FBI and taken into US custody.

Mr Barr told me he didn't know the details.

He said it could have been with the explicit or tacit consent of the Libyan government, or it could have been without their consent at all.

Mr Barr said he has always been confident that the US would get to Mr Masud, because the current Libyan government has no reason to align itself with the people who plotted the worst terror attack in UK history.