On December 21, 1988, Pan Am Flight 103 took off from Heathrow Airport in London bound for New York City. Among the 259 passengers and crew were 190 Americans.

They never made it home. Less than 40 minutes into the flight, the plane exploded over Lockerbie, Scotland, killing everyone on board and 11 Scots on the ground.

Until 9/11, it was one of the world’s most lethal acts of air terrorism and one of the largest and most complex acts of international terrorism ever investigated by the FBI.

Solving the case required unprecedented international cooperation. The explosion at 30,000 feet rained debris over 845 square miles, creating the largest-ever crime scene. More than 5,000 responders, including investigators from the FBI and Scottish authorities, combed the countryside for clues. They recovered 319 tons of wreckage and thousands of pieces of evidence. In the ensuing years, investigators traversed the globe, interviewing more than 10,000 individuals in 16 countries.

In the debris, investigators found a tiny fragment that helped establish that the bomb had been placed inside a radio in a piece of luggage aboard Pan Am 103. Another small fragment, found embedded in a piece of shirt, helped identify the explosive timer. This evidence led to two Libyan intelligence operatives.

In 1991, the British and American governments charged Abdel Basset Ali al-Megrahi and Lamen Khalifa Fhimah in the case. Their trial in 2000 was held in Scottish court built for the occasion on a former U.S. military base in the Netherlands. The court acquitted Fhimah and convicted al Megrahi in 2001, sentencing him to life in prison. He was released in 2009 when he was believed near death from cancer, but he survived almost three more years.

The Libyan government formally accepted responsibility for the bombing and agreed to pay nearly $3 billion to the victims’ families.

Since the bombing, victims’ families have continued to push to advance the investigation, believing the plot and its execution were not limited to Fhimah and al Megrahi.

Agents in the Washington Field Office made repeated trips to countries with a nexus to the plot. And in private briefings, FBI officials steadfastly assured victims’ families the investigation was robust and ongoing. On December 21, 2020—32 years to the day after the terrorist bombing—federal officials charged a third person, Abu Agela Mas’ud Kheir Al-Marimi, in the case. Abu Agela Mas’ud Kheir Al-Marimi was arrested in 2022.

Learn more in our 2018 coverage marking the 30th anniversary of the bombing.