The brave mujahideen in Iraq have slaughtered another helpless hostage: Video on Web Site Shows Beheading of Man.

BAGHDAD, Iraq - A video posted Monday on a Web site showed the beheading of a man identified as American civil engineer Eugene Armstrong. The militant group led by Abu Musab al-Zarqawi claimed responsibility for the slaying and said another hostage — either an American or a Briton — would be killed in 24 hours.

The grisly decapitation was the latest killing in a particularly violent month in Iraq, with more than 300 people dead in insurgent attacks and U.S. military strikes over the past seven days. Earlier Monday, gunmen in Baghdad assassinated two clerics from a powerful Sunni Muslim group that has served as a mediator to release hostages.

The video of the beheading of the man believed to be Armstrong surfaced soon after the expiration of a 48-hour deadline set earlier by al-Zarqawi’s Tawhid and Jihad group for the beheading of the three civil engineers. The men — Armstrong, American Jack Hensley and Briton Kenneth Bigley — were abducted Thursday from their home in a wealthy Baghdad neighborhood.

A militant whose voice resembled al-Zarqawi, who has been linked to al-Qaida, read a statement in the video saying the next hostage would be killed in 24 hours unless all Muslim women prisoners are released from U.S. military jails.

“You, sister, rejoice. God’s soldiers are coming to get you out of your chains and restore your purity by returning you to your mother and father,” he said before grabbing the hostage, seated at his feet, and cutting his throat. …

The 9-minute tape, posted on a Web site used by Islamic militants, showed a man seated on the floor, blindfolded and wearing an orange jumpsuit — similar to the orange uniform worn by prisoners at the U.S. naval base in Guantanamo Bay, Cuba — with his hands bound behind his back. Five militants dressed in black stood behind him, four of them armed with assault rifles, with a black Tawhid and Jihad banner on the wall.

The militant in the center read out a statement, as the hostage rocked back and forth and side to side where he sat. After finishing, the militant pulled a knife and cut his throat until the head was severed.

The victim gasped loudly as blood poured from his neck. His killer held up the head at one point, and placed it on top of the body.

“The fate of the first infidel was cutting off the head before your eyes and ears. You have a 24-hour opportunity. Abide by our demand in full and release all the Muslim women, otherwise the head of the other will follow this one,” the speaker said.