WASHINGTON (CBS/CNN) — The United States has announced new criminal charges in the terrorist bombing of Pan Am flight 103 over Lockerbie, Scotland. They are against former Libyan intelligence officer Abu Agila Masud, who is accused of making the bomb, Attorney General William Barr said Monday morning.

Monday is the 32nd anniversary of the attack, which killed 270 people, the majority of whom were Americans. The Pan Am Boeing 747 was en route from London to New York. A memorial website lists 15 victims of the crash who were from Massachusetts or New Hampshire.

Libyan leader Moammar Ghadafi later accepted Libya’s responsibility for the bombing.

“The breakthrough that led to the charges announced today arose when law enforcement learned in 2016 that the third conspirator had been arrested after the collapse of the Ghadafi regime and had been interviewed by Libyan law enforcement,” Barr said at a news conference. “According to the criminal complaint affidavit, Masud built the bomb that destroyed Pan Am 103.”

Jeannine Boulanger, of Shrewsbury, lost her daughter Nicole in the bombing.

“It certainly is a major step and it’s something that is very meaningful to the families of the victims,” Boulanger said Monday in reaction to the new charges.

Nicole Boulanger, who died in the Pan Am Flight 103 explosion (WBZ-TV)

Early in his tenure at the department under President George H.W. Bush, Barr had announced charges against two other Libyan intelligence-linked men, Abdelbeset Ali Mohmed al Megrahi and Al Amin Khalifah Fhimah, whom the US accused of placing explosives in a portable cassette and radio player that was inside a suitcase on the plane.

But because of difficulty bringing them to the US, the men were tried instead by a Scottish court sitting in neutral Netherlands.

The trial resulted in an acquittal of Fhimah and a conviction of Megrahi. Megrahi, sentenced to 27 years in prison, was released from prison after being diagnosed with cancer. He died in 2012.

The new case is expected to be filed by prosecutors in Washington, DC.

Masud is believed to be in Libya. But US authorities have plotted out a less complicated court procedure than before.

Officials say the US is having conversations with Libya to take custody of Masud, and with Scottish authorities who may be able to provide evidence.

(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. CNN’s Katelyn Polantz and Evan Perez contributed to this report.)