Libyan Abu Agila Mohammad Masud has been charged in a US court in relation to the 1988 Lockerbie bombing which killed 270 people.
The intelligence official faces two criminal counts over the bombing, which happened 32 years ago today.
In 2001, another Libyan intelligence officer, Abdelbaset al-Megrahi, was convicted of the attack on Pan Am flight 103 after it exploded over the Scottish town of Lockerbie.
He was given a life sentence, but was released on humanitarian grounds in 2009 due to suffering prostate cancer. He later died in Tripoli.
Most victims on the London to New York flight were American citizens.
Last week, The Wall Street Journal reported that Mohammad Masud was in custody in Libya and that outgoing US Attorney General William Barr was seeking his extradition to the US to stand trial.
That development received a guarded welcome by Jim Swire, whose daughter Flora died in the bombing.
He had told Sky News: "I'm all in favour of whatever he's got to tell us being examined in a court, of course I am."
"The more people who look at the materials we have available the better because there are only two things that we seek, really.
"One is the question of why those lives were not protected in view of all the warnings and the second is: what does our government and the American government really know about who is responsible for murdering them."
The case is likely to be of special significance to Mr Barr, as it is the second time he has overseen charges in connection with the bombing.
He held the same job when the Justice Department indicted Megrahi and a second Libyan, Lamen Khalifa Fhimah, for building a plastic bomb with a timer before hiding it inside a suitcase and planting it on an Air Malta flight.