Terrorist Chief Said Killed After Hostage Beheaded

According to Saudi spokesmen, the operation drew on 15,000 security personnel, including fire departments familiar with streets and neighborhoods. More than 1,200 homes had been searched by Thursday night.

In addition, the U.S. government dispatched 20 FBI agents to Saudi Arabia to assist in the search. The presence of American agents on Saudi soil was a sensitive subject for Saudi government officials, who played down the U.S. role and bristled at the suggestion that they were unable to control the insurgency.

Prince Nayef, the Saudi interior minister, said in an interview with the French newspaper Le Figaro that the Saudi government did not need outside assistance. He noted that the United States has had difficulty finding terrorist suspects elsewhere, singling out Abu Musab Zarqawi, a radical who has eluded capture in Iraq despite a $25 million reward offer. Zarqawi has claimed responsibility for beheading another American, Nicholas Berg, in a kidnapping in Iraq this year.

In the days leading up to the deadline, Johnson's relatives and friends made emotional appeals on television for his release, telling the kidnappers that he was a friend of Muslims and deeply interested in their culture.

"Please release my father," Johnson's son, Paul Johnson III, told al-Arabiya television a few hours before the station reported the execution. "He is an innocent man. He loves Muslims. Saudi Arabia was his home." Johnson's wife, Thanom, made a similar plea in television interviews.

On Friday, the kidnappers posted a statement on an Islamic Web site announcing his death and included three photos of his remains.

Johnson worked on Apache attack helicopter systems for the Saudi government. His kidnappers said he was singled out for that reason. "Let him taste something of what Muslims have long tasted from Apache helicopter fire and missiles," they said in a statement posted on the site. "The infidel got his fair treatment."

"To the Americans and whoever is their ally in the infidel and criminal world and their allies in the war against Islam, this action is punishment to them and a lesson for them to know that whoever steps foot in our country, this decisive action will be his fate," the statement said.

James C. Oberwetter, the U.S. ambassador to Saudi Arabia, confirmed Johnson's death. "The inhumanity of the crime exceeds all boundaries of civilized peoples," he said in a statement.

On Thursday, the U.S. Embassy in Riyadh issued a fresh warning to Americans in Saudi Arabia, saying that there was "credible information indicating that extremists are planning further attacks against U.S. and Western interests." The warning added that Americans living in private residences -- as opposed to the guarded compounds that house many expatriates -- were being "specifically targeted."

On April 15, the State Department urged all Americans to leave the kingdom and has ordered the evacuation of all non-essential embassy personnel. For the past two months, all Americans remaining in Saudi Arabia have been asked to register their presence with the embassy.

In a radio interview Friday, Secretary of State Colin Powell said he hoped new security measures "will encourage people to stay" in Saudia Arabia. "If they leave, then the terrorists have won," Powell said on "The Michael Reagan Show." "And I don't think either the Saudis, the Americans, or these brave folks who work in Saudi Arabia want the terrorists to win."

American workers, most of them with the oil industry, and dependents used to number close to 35,000. Embassy officials said on Friday they did not know how many had left.

Lockheed began evacuating employees' family members from the country in April after the State Department issued its warning. Lockheed, the Pentagon's largest contractor, declined to say how many of its workers remained in Saudi Arabia or to discuss what security precautions it was taking.