Abu Agila Mohammad Mas’ud has been arrested by the FBI and is being extradited to the United States. He is accused of building the explosive device used in the bombing of Pan Am Flight 103. The 1988 bombing over Lockerbie killed 270 people, including 190 Americans. Libyans Abdel Basset Ali al-Megrahi and Al-Amin Khalifa Fhimah were charged in 1991 with the bombing. American efforts to prosecute them originally ran aground when Libya declined to send them to the U.S. or Britain, Adam Goldman reports for the New York Times