Updated December 11, 2022 at 4:36 PM ET

U.S. authorities have apprehended a Libyan man suspected of constructing the bomb that destroyed a passenger plane over Lockerbie, Scotland in 1988, killing 270 people, including 190 Americans.

"The United States has taken custody of alleged Pan Am flight 103 bombmaker Abu Agila Mohammad Mas'ud Kheir Al-Marimi," a spokesperson for the Department of Justice said in a statement to NPR.

Scotland's Crown Office and Procurator Fiscal Service confirmed that the families of those killed in the bombing have also been notified of the arrest.

"Scottish prosecutors and police, working with UK Government and US colleagues, will continue to pursue this investigation, with the sole aim of bringing those who acted along with Al Megrahi to justice," the office said in a statement.

On Dec. 21, 1988, Pan Am Flight 103 exploded into pieces over Lockerbie, Scotland after a bomb was placed in the cargo area of the plane. The bombing was the single deadliest terror attack in the history of the United Kingdom, and the second deadliest for Americans after Sept. 11, 2001. The plane had taken off from London and was on its way to John F. Kennedy Airport in New York.

According to federal officials, passengers and crew from 21 different countries were killed in the attack. Of the 190 Americans who died, 35 of them were students from Syracuse University in upstate New York who were returning home for the holidays after a semester studying abroad.

The attack launched a decades-long international manhunt for the bomb-makers.

In 2020, U.S. authorities announced a breakthrough in the case — they discovered that Libyan authorities had apprehended Mas'ud, a former Libyan intelligence operative, and interviewed him about his involvement in the bombing. During that interview, Mas'ud admitted to building the bomb that brought down the plane, according to the Justice Department.

In 2020, the Justice Department charged Mas'ud with destruction of an aircraft resulting in death and destruction of a vehicle by means of an explosive resulting in death.

The department says he will make his initial court appearance in the U.S. District Court for the District of Columbia.

Kara Weipz, whose brother, Richard Monetti, was killed in the Lockerbie bombing, said she is especially encouraged to know that the suspect is in U.S. custody.

"This means so much to the families, so much to my family, so much to me to know that justice for my brother, for the 269 other victims is going to be served in our country under our laws," Weipz, who is also the president of the group Victims of Pan Am Flight 103, told NPR's Michel Martin on All Things Considered.

Mas'ud is believed to have set the timer on the explosive

Federal officials said Mas'ud was summoned by Libyan authorities in the winter of 1988 to travel to Malta with a suitcase used to carry out the attack. He was joined in Malta by two other Libyan intelligence agents, Abdel Basset Ali al-Megrahi and Lamen Khalifa Fhimah, according to the Justice Department.

There, Masud was instructed to prepare the timer inside the suitcase so that an explosion would detonate exactly 11 hours later. The next day, at the airport, Mas'ud handed off the suitcase to Fhimah who then placed the luggage onto a conveyor belt, according to the Justice Department. Mas'ud and the two others returned to Libya, where former Libyan dictator Muammar Gaddafi, thanked them for carrying out the operation, according to federal officials.

The Lockerbie bombing is considered one of the most complicated investigations in U.S. history

The FBI said that the Lockerbie case was one of the most complex investigations they have ever worked on. Investigators interviewed more than 10,000 people around the world and analyzed the largest crime scene in recent history — about 845 square miles of scattered debris.

In the rubble, authorities found two tiny fragments that helped trace the bomb to a radio inside an item of luggage and the explosive's timer to a shirt.

In 1991, U.S. and British governments charged Megrahi and Fhimah, the two Libyan intelligence agents suspected of working with Mas'ud. They were tried in Scottish court a decade later, where Fhimah was acquitted and Megrahi was sentenced to life in prison.

In 2009, in a highly controversial move, the Scottish government allowed Megrahi to return to Libya on compassionate grounds after he became terminally ill with prostate cancer.

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