Terrorist Chief Said Killed After Hostage Beheaded

"Paul bravely carried out his duties, and the news of his sudden loss is a shock to everyone in the Lockheed Martin family," the firm's two top executives, Chairman and CEO Vance Coffman and President Robert J. Stevens, said in a memo to employees. "We grieve along with his family."

Lockheed employees have sent 700 e-mails and letters to Johnson's family during the last week expressing remorse and condolences, according to company spokesman Tom Jurkowsky. "It's a different mood around here. It's numbing," Jurkowsky said.

Saudi Arabia is the birthplace of al Qaeda founder Osama bin Laden and the leading financial backer of conservative Islamic causes around the world. From the late 1970s until 2001, an estimated 15,000 Saudis trained at camps in Afghanistan and helped fuel religious warfare across the Middle East and northern Africa.

While many militant leaders, including bin Laden, have labeled the Saudi royal family corrupt for years and called for its ouster, until last year the kingdom was largely spared attacks from within. Violence picked up last May, when local groups allied with al Qaeda mounted a car bomb attack on a Western residential compound in Riyadh, killing 35 and sparking a limited but open revolt against the government.

Saudi security officials said they have arrested more than 300 militants since then and broken up the biggest terror cells, but have not been able to contain the violence. The attacks helped drive oil prices to historic highs and raised speculation that the House of Saud's hold on power might be slipping.

Muqrin's group is believed to have been behind a hostage-taking attack on a Western residential compound in Khobar last month that left 22 dead, as well as a suicide bombing in Riyadh last November that killed 17 and wounded more than 120.

Since then, the radicals have changed their tactics and have opted to target individual, unprotected Westerners rather than attempting to inflict mass casualties.

Mustafa Alani, a Middle East security analyst at the Royal United Services Institute in London, said the group wanted to avoid harming Muslims for fear of creating a backlash in the region. He also said that more kidnappings were likely.

"This sort of operation is easy to execute," he said in a telephone interview. "It's also cheap and very effective. How hard is it to shoot or grab somebody on the street? Look at all this television coverage they've gotten in the U.S. They've now discovered this cheap and easy way to get publicity."

Stencel reported from Washington. Staff writer Renae Merle in Washington contributed to this report.