Scottish prosecutors are seeking to question Libya's ex-foreign minister Moussa Koussa, who defected on Wednesday, about his knowledge of the 1988 bombing of Pan Am 103 over Lockerbie, Scotland.
The move is the latest and most public sign yet that the investigation into the Lockerbie bombing has been revived -- and may be used by U.S. and British officials in an effort to force Moammar Gadhafi's removal from power. Asked about the Scottish request to question Koussa, a U.S. Justice Department spokesman said Thursday: "We're on it. The investigation is open and active." U.S. law enforcement officials also "are extremely interested" in talking to Koussa, the official added.Story: What you need to know about the unrest in the Mideast
In an email sent Thursday to family members of the Lockerbie bombing victims, Lindsey Miller, the Scottish prosecutor on the case, said her office had notified the British Foreign Office that "we wish to interview (Koussa) regarding any information he may have concerning the bombing of Pan Am flight 103."
The email also stated that the investigation into the Lockerbie bombing "remains open and we will pursue all relevant lines of inquiry in conjunction with our U.S. counterparts."
Koussa, 73, is considered by law enforcement officials and family victims as a potentially crucial witness in the Lockerbie case, one of the few regime intimates who would be in a position to corroborate the recent claims of Libya's ex-justice minister that Gadhafi ordered the destruction of the civilian aircraft.
A longtime senior Libyan intelligence official and close confidant Gadhafi, the U.S. educated Koussa fled to Britain on Wednesday on a private plane from Tunisia.Story: Libya's foreign minister defects
"His testimony would be critical," said Frank Duggan, president of a group of Lockerbie victims’ families. "He has intimate knowledge — not only who ordered the bombing, but about the bomb (that blew up the plane])and who made it.”
British Foreign Minister William Hague told reporters in London that Koussa "is not being offered any immunity from British or international justice."
But some family members of the victims remain suspicious that Koussa has been offered some sort of protection by British authorities.
"What I'm afraid of is they've already made a deal with him," said Stephanie Bernstein, whose husband, a Justice Department lawyer, was killed in the Lockerbie bombing. She said she and other family members would be strongly opposed to any move that would protect Koussa from prosecution. "This man has an unbelievable amount of blood on his hands," she said.Story: The two faces of Gadhafi's right-hand man
A spokesman for the British Foreign Office told NBC News that Koussa was now at a "safe location in the United Kingdom." The spokesman did not immediately respond for comment on the request by Scottish prosecutors to question him.
The push to revive the Lockerbie investigation is also gaining momentum in Congress and among some Libyan dissidents as one possible way to force Gadhafi from power. One scenario being discussed on Capitol Hill is for federal prosecutors — based on new evidence — to indict Gadhafi for the Lockerbie bombing, thereby conceivably giving the FBI or even the U.S. military grounds to snatch him as a fugitive from justice.
There is a possible precedent: the U.S. invaded Panama in 1989 in part on grounds that the country's then dictator, Manuel Noriega, was a fugitive from a federal drug trafficking indictment brought by federal prosecutors in Miami.
The White House did not immediately respond to a request for comment on whether such a move was being contemplated.
In a letter to U.S. Attorney General Eric Holder on Thursday, Sen. Lindsey Graham, R-S.C., called for the Justice Department to step up the pressure on Gadhafi by specifically targeting him in the Lockerbie investigation. Citing the recent claims by former Libyan Justice Minister Mustafa Abdel-Jalil that Gadhafi ordered the bombing, Graham wrote, “Should the claims ... prove true, he should be punished to the fullest extent of the law."
In a separate letter Thursday to Secretary of State Hillary Clinton, Sen. Charles Schumer, D-N.Y., said that any support for Libyan rebels be conditioned on their commitment to extradite Abdel Baset al-Megrahi to New York to be tried in U.S. court for the Lockerbie bombing.
A former Libyan intelligence agent, Megrahi was the only person ever convicted of the bombing, but was released by Scottish officials in 2009 on "compassionate" grounds that he was suffering from prostate cancer and had only three months to live. But he is still believed to be alive in Libya, protected by Gadhafi's regime.
© 2013 NBCNews.com Reprints