WASHINGTON -- The U.S. Justice Department has unsealed charges accusing a Libyan bomb expert in the 1988 explosion of Pan Am Flight 103 over Lockerbie, Scotland, that killed 259 people in the air and an additional 11 on the ground.

The charges were announced on the 32nd anniversary of the bombing and in the final news conference of Attorney General William Barr's tenure, underscoring his personal attachment to a case that unfolded during his first stint at the Justice Department.

Barr announced an earlier set of charges against two Libyan intelligence officials in his capacity as acting attorney general nearly 30 years ago, vowing that the investigation would continue.

Though he had not appeared at a press conference in months, Barr led this one two days before his departure as something of a career bookend.

In presenting new charges, the Justice Department is revisiting a case that deepened the chasm between the United States and Libya, laid bare the threat of international terrorism more than a decade before the September 11th attacks and produced global investigations and punishing sanctions.