The US Justice Department plans to soon unseal new charges in connection with the 1988 bombing of a Pan Am jet that exploded over Lockerbie, Scotland, killing 270 people, a source said.
The bombing of Flight 103, the victims of which included dozens of American university students, spurred global investigations and sanctions against Libya.
Libya ultimately surrendered two intelligence officials for prosecution before a Scottish court sitting in the Netherlands.
The announcement of a prosecution against an another person would carry personal significance for Attorney General William Barr, who is leaving the position next week.
But he held the same job when the Justice Department nearly 30 years ago revealed criminal charges in the US against the two Libyans.
Monday is the 32nd anniversary of the bombing.
“This investigation is by no means over," Mr Barr said in 1991 while announcing the charges. "It continues unabated.
"We will not rest until all those responsible are brought to justice. We have no higher priority.”
The head of the Justice Department’s criminal division at the time was Robert Mueller, who went on to serve as FBI director and special counsel in charge of the investigation into ties between Russia and the 2016 Trump campaign.
Libya refused to extradite the two men to the US but later agreed to a deal to put them on trial in the Netherlands.
News of the expected criminal case was first reported by The Wall Street Journal and The New York Times.
The flight to New York exploded over Lockerbie less than an hour after takeoff from London on December 21, 1988.
Among the Americans on board were 35 Syracuse University students flying home for Christmas after a semester abroad.
The attack, caused by a bomb packed into a suitcase, killed 259 people on the plane and 11 on the ground.
In 1992, the UN Security Council imposed arms sales and air travel sanctions against Libya to pressure Muammar Qaddafi, the country’s leader, into surrendering the two suspects.
The sanctions were later lifted after Libya agreed to a $2.7 billion compensation deal with the victims’ families.
Former Libyan intelligence official Abdelbaset Al Megrahi was convicted of the bombing and the second suspect was acquitted of all charges.
Al Megrahi was given a life sentence, but Scottish authorities released him on humanitarian grounds in 2009 when he had prostate cancer diagnosed. He later died in Tripoli.