Washington (CNN) -- The release of convicted Pan Am Flight 103 bomber Abdelbeset al-Megrahi from a Scottish prison last year was a "grievous mistake," a U.S. senator said Wednesday.
Sen. Robert Menendez, D-New Jersey, apologized for "inconveniencing those who would rather sweep this under the bin," but said he wanted to shed light on the "troubling circumstances" surrounding al-Megrahi's release by the Scottish government last year on the grounds that he had cancer and was not likely to live more than three more months.
Al-Megrahi is the only person convicted in the bombing of Pan Am Flight 103, which exploded over Lockerbie, Scotland, in December 1988, killing 259 people on the plane and 11 on the ground.
Menendez is chairing an investigation looking into al-Megrahi's release. On Wednesday, the Senate Committee on Foreign Relations held a hearing on the circumstances of his release.
Nancy McEldowney, the deputy assistant secretary of European affairs at the State Department, told the committee that the United States never approved of the release.
Sen. Frank Lautenberg, D-New Jersey, said it is ironic that al-Megrahi was shown compassion, after showing none to his victims.
Most of the dead were Americans. The flight was heading to New York from Frankfurt, Germany, via London, England, when it blew up.
A special Scottish court in the Netherlands convicted al-Megrahi in 2001.
After his release in August 2009, al-Megrahi returned to Libya. Jim Swire, whose daughter Flora died in the bombing, said last week that al-Megrahi is sick but alive and that he saw him in Libya in early September.