Saudis search for kidnappers of American

The account highlighted fears that some diplomats and Westerners in the kingdom have expressed, that militants have infiltrated Saudi security forces, a possibility Saudi officials have denied.

Saudi King Fahd vowed that militants in the kingdom would be stopped.

''The perpetrators of these attacks aimed at shaking stability and crippling security -- and it is a farfetched aim, God willing," he said in a speech yesterday to the advisory Shura Council. ''We will not allow this destructive bunch, led by deviant thought, to harm the security of this nation or affect its stability."

Police barricaded off the al-Malaz district in Riyadh, where security forces were surrounding the house. Witnesses said they saw shooting between suspects and police before some men fled on foot, seeking refuge in the building.

It was the same area where Abd Al Aziz Al-Moqrin, believed to be the leader of Al Qaeda in Saudi Arabia, and three other militants were killed in a shootout with Saudi security forces Friday, hours after their cell killed Johnson and posted photos of his body and severed head on a website.

The foreign affairs adviser of Crown Prince Abdullah in Washington, Adel al-Jubeir, said Saudi officials were still looking for Johnson's body. ''We are still combing through neighborhoods. And we hope that eventually we'll find the body and restore it to his family," he told CNN's ''Late Edition."

According to the account of Johnson's kidnapping, militants wearing police uniforms and using police cars set up a fake checkpoint June 12 on al-Khadma Road, leading to the airport, near Imam Mohammed bin Saud University.

''A number of the cooperators who are sincere to their religion in the security apparatus donated those clothes and the police cars. We ask God to reward them and that they use their energy to serve Islam and the mujahedeen," the article read.