Riyadh, Saudi Arabia ? Saudi security agents searched homes in the capital and surrounding deserts Saturday for the body of slain American hostage Paul M. Johnson Jr., while Saudi officials hailed as a victory their slaying of his executioner, the top al-Qaida figure in the kingdom.

But the U.S. ambassador said he doubted the death of Abdulaziz al-Moqrin during a Friday night shootout would stop the ongoing violence against Westerners in Saudi Arabia.

Militants initially denied that al-Moqrin was killed, but late Saturday the al-Qaida cell in Saudi Arabia confirmed his death in an online statement. The group also vowed to continue its “jihad,” or holy war.

Saudi officials initially said Johnson’s body was found Friday dumped on the capital’s northern outskirts, hours after his captors killed and decapitated him and posted Web photos of his severed head.

But officials backtracked Saturday.

“We haven’t found the body yet,” said Adel al-Jubeir, foreign affairs adviser to Crown Prince Abdullah, in Washington. “We think we know the area where it is.”

Saudi security officials said on condition of anonymity they were searching desert areas around Riyadh and dwellings they suspect were used by militants.

Johnson, 49, was taken last weekend by militants who threatened to kill him if the kingdom did not release al-Qaida prisoners. The Saudi government rejected the demands.

Three photos of Johnson’s body, the head severed, were posted on the Internet when the deadline expired. The photos were accompanied by a statement from the Fallujah Brigade of al-Qaida in the Arabian Peninsula that said “the infidel got his fair treatment. …Let him taste something of what Muslims have long tasted from Apache helicopter fire and missiles.”

Johnson worked on Apache helicopters for Lockheed Martin.

Al-Moqrin, the most-wanted man in the kingdom, and three other militants were killed in a shootout hours after Johnson’s death was reported.

Forces also killed Faisal al-Dukheil, “who is believed to be the No. 2 al-Qaida person in Saudi Arabia,” al-Jubeir said. The other slain militants included Turki bin Fuheid al-Muteiry and Ibrahim bin Abdullah al-Dreiham.

Al-Moqrin, who trained in Afghanistan, took over al-Qaida operations in the kingdom after his predecessor, Khaled Ali Haj, was killed by security agents earlier this year. Al-Moqrin is believed to have led the recent campaign of violence against foreigners.

“This was a major blow to al-Qaida in Saudi Arabia,” al-Jubeir said.

But he acknowledged that there likely are other al-Qaida cells in the kingdom seeking to topple the royal family for its close ties to the United States.