The United States on Monday unsealed criminal charges against a third alleged conspirator in the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, that killed 270 people, mostly Americans.

The suspect, Abu Agila Mohammad Masud Kheir Al-Marimi, a former senior Libyan intelligence official, was charged with two criminal counts related to the bombing. He is in Libyan custody, U.S. Attorney General William Barr said, adding that U.S. officials are hopeful that Libya will allow Masud to be tried in the United States.

“No amount of time or distance will stop the United States and our Scottish partners from pursuing justice in this case,” Barr told a news conference Monday.

The Justice Department said Masud carried the bomb that eventually blew up the plane from Libya to Malta in a suitcase and then set the device’s timer.

It said that from around 1973-2011 Masud worked for Libyan intelligence, including as a bomb-making expert. It alleged Masud was involved in the 1986 bombing of the LaBelle Discotheque in West Berlin, Germany that killed two U.S. service members.

In 1991, two other alleged Libyan intelligence operatives were charged in the Lockerbie bombing: Abdel Baset Ali al-Megrahi and Lamen Khalifa Fhimah.

Megrahi was found guilty of the Lockerbie bombing in 2001 by a Scottish court which convened in the Netherlands. He was jailed in Scotland but later was allowed to return to Libya on compassionate grounds before dying of cancer in 2012. The Scottish court found Fhimah not guilty.

Barr said the breakthrough that led to charges against Masud came after the U.S. learned in 2016 that he “had been arrested after the collapse of the Qaddafi regime and interviewed by a Libyan law enforcement officer in September 2012.”

The Justice Department said late Libyan leader Muammar Qaddafi personally thanked Masud and Fhimah for attacking the American target, and that Qaddafi described the operation as a total success.