In the time-honored manner, a dozen men and boys fell to their knees, facing Mecca, to intone their daily prayers at the Mosque al-Noor. But the ordinary prayer session Monday included an extraordinary appeal: a plea for the safety of Wassef Ali Hassoun, a member of this small mosque who is facing a death threat from militants in Iraq.

The tightly knit Islamic community in the southwest suburbs of Salt Lake City responded in shock and fear Monday to news that Hassoun, a U.S. Marine corporal with extensive family ties here, had been captured by a group calling itself the Islamic Retaliation Movement/Armed Resistance Wing. In a videotape released Sunday, showing Hassoun, 24, in a blindfold with a crescent-shaped blade over his neck, the group said the Marine will be beheaded unless all detainees held by the U.S. military in Iraq are freed.

"In the name of Allah, the merciful, the compassionate, we accept destiny, with its good and bad," said Tarek Nasseir, a member of the Salt Lake City mosque serving as a spokesman for Hassoun's relatives here.

"We pray and we plead for his safe release," Nasseir said. "And we ask all people of the world to join us in our prayers. May God bless us all."

In the suburb of West Jordan, where Hassoun had lived with some of his brothers in a new subdivision at the foot of the snow-capped Wasatch range, the Marine's family told local police that it had received no information about the captive beyond the few seconds of video released by the militants.

"Their mood is somber," West Jordan Police Chief Gary Cox told reporters swarming the street outside the Hassoun family's large two-story home. "They have no information."

That left nothing to do but pray, and various faiths here in the capital city of the global Mormon faith were doing exactly that on Monday. The Mosque Khadeeja, a suburban Islamic center where the Hassoun family regularly worships, held a prayer vigil for the captured Marine on Monday night. Mormon and other Christian leaders, meanwhile, gathered on the steps of the state Capitol in downtown Salt Lake City for an evening prayer session asking for Hassoun's safe return.

Cox, the local police chief, said Hassoun's relatives did not know he was missing from his base in Iraq until they saw the frightening image of the Marine on television Sunday. But military officials in Iraq said the corporal had been missing since June 20.

As is common in Muslim communities across the United States, members of the faith here have been strongly critical of the U.S. invasion of Iraq. That feeling was not hidden at the Mosque Khadeeja prayer service Monday.

"We are praying for all those people held captive against their will in Iraq," said Nameed Ahmed, a member of the mosque's governing council, "including those being held by the U.S. soldiers. We are against those who are holding our brother in Iraq, but we are also against the war that sent Mr. Hassoun to fight there."

Hassoun had gone "on an unauthorized absence," Brig. Gen. Mark Kimmitt, the coalition deputy operations chief in Baghdad, told reporters in Iraq. "Based on his personal situation, there was reason to suspect that he was heading over to Lebanon."

Family members told the Associated Press that Hassoun was born in Lebanon and attended the American School there. His family is prominent in Lebanon, and relatives there were reportedly endeavoring to get word to the militant group holding the Marine.

"We are trying to send word through all channels that he is Lebanese, Arab and a Muslim," Abdullah Hassoun, another member of the extended family and the head of Al-Safira municipality in Lebanon, told the Associated Press.

Wasef Hassoun apparently moved to Utah to join some of his brothers in the Salt Lake suburbs two years ago. He joined the Marines shortly thereafter. Those who knew him here were unclear about when he went to Iraq.