Alleged Plot to Kill Saudi Ruler Detailed

"We are at a very delicate stage in the investigation," one U.S. law enforcement official said.

Authorities hope that word of Alamoudi's cooperation with the government will encourage those who had worked with him in support of Hamas and other extremists to volunteer information to investigators, one law enforcement official said.

"Now that everyone knows Alamoudi is talking, subjects of other investigations may come in," the official said. "They know he has a lot to tell us."

News of the investigation has shocked Muslim activists who worked closely with Alamoudi, the founder of numerous U.S. Islamic groups including the American Muslim Council, and an occasional White House visitor during the Clinton and current administrations.

The plot, first disclosed yesterday by the New York Times, began in May 2003, when Alamoudi met in Libya with Gaddafi, who said he wanted Abdullah killed, according to Alamoudi's account, the sources said. At a meeting in June, Gaddafi asked Alamoudi why there had not been any "heads flying" in the Saudi royal family, the sources said.

Later last year, Ismael and Alamoudi were in touch with Saudi dissidents in London, who helped locate men in Saudi Arabia willing to join an assassination plot that involved the use of small arms or rocket-propelled grenades, according to people familiar with the case.

Ismael subsequently traveled to Egypt, where he was arrested by security officers. On Nov. 27, Saudi participants who had been recruited by Ismael were arrested at a hotel in Mecca as they waited to receive cash payments from their Libyan handlers.

Among the people under investigation in Britain is Faqih, the dissident leader who has had close contacts with Saudi extremists and jihadists for years but who professes to embrace only peaceful reform, officials said. Yesterday, he acknowledged having known Alamoudi for years but denied being funded by him or by Ismael.

U.S. authorities first learned of allegations that Libyans were working with militant Saudi dissidents in November, eight months after Libya approached the British government about ending its weapons programs. The Americans raised concerns about those allegations in December, during the weapons negotiations in London.

Libya ultimately allowed U.S. authorities to remove its nuclear components and opened its doors to international inspectors. Early this year, Assistant Secretary of State William Burns discussed "the issue of using violence for political means" with Gaddafi in Tripoli, according to Boucher.

In April, Bush eased economic sanctions, opening the door to U.S. oil companies, banks and other investors to resume business that had been prohibited since 1986.

The Bush administration remains confident about Libya's cooperation on eliminating its illicit weapons programs. U.S. authorities hauled out large amounts of equipment from Libya, including tons of uranium-enrichment equipment, now under lock and key in Tennessee.

U.N. inspectors have gone from town to town in the desert nation in search of information about Libya's scientific and manufacturing capabilities. They have concluded that Libya's nuclear program was quite limited and now seems to pose little danger.

Staff writers Susan Schmidt, Mary Beth Sheridan, Jerry Markon and Dana Milbank contributed to this report.