A video purportedly showing a British hostage pleading for his life was posted on an Islamic Web site on Wednesday, hours after U.S. officials confirmed that a second American hostage was slain this week.

"To Mr. Blair, my name is Ken Bigley (search), from Liverpool," the man said in the grainy videotape. "I think this is possibly my last chance. I don't want to die."

"Please, please, release the female prisoners that are held in Iraqi prisons," the speaker said, addressing British Prime Minister Tony Blair. "Please help them. I need you to help me Mr. Blair because you are the only person now on God's Earth that I can speak to. Please, please help me see my wife, who cannot go on without me."

The speaker wore an orange jumpsuit, the kind that kidnappers in Iraq have put on their hostages before killing them. He sobbed in the middle of his message and wiped his forehead.

Meanwhile, a Reuters report on the deaths of two female Italian hostages could not immediately be confirmed. An Islamist group claimed to have killed the two aid workers, who were grabbed from their office in Baghdad more than two weeks ago.

Earlier on Wednesday, the headless body of Jack Hensley (search), one of two Americans taken hostage with Bigley last week, was found in Iraq and handed over to U.S. officials.

"The FBI has confirmed that the body found today in Baghdad is that of U.S. citizen Jack Hensley. We condemn in the strongest possible terms this despicable act of terrorism," a State Department spokeswoman said.

"This is a terrible tragedy that illustrates the ruthless nature of those who committed this crime. We extend our deepest condolences to Mr. Hensley's family in their time of loss."

Also on Wednesday, a video purportedly showing kidnappers beheading Hensley appeared on an Islamic Web site.

A blindfolded man wearing an orange jumpsuit was seen sitting in front of five masked terrorists dressed in black. One read a statement as they stood in front of a Tawhid and Jihad (searchbanner.

After the man finished reading the statement, a terrorist pulled a knife and attacked the man from behind. Then the head was placed on the body.

Hensley was an American worker from Marietta, Ga., who would have celebrated his 49th birthday on Wednesday. He had come to Iraq to support his wife and 13-year-old daughter but was kidnapped along with two other contractors last Thursday.

The Hensley family was given the news Wednesday, said Cobb County spokesman Robert Quigley outside of Hensley's Marietta, Ga., home.

"They killed the wrong man," Hensley's brother, Ty Hensley, told FOX News on Wednesday. "They killed my t-ball coach. They killed a volunteer on a rescue squad. They killed a man who worked three jobs to keep his family going."

Family members have established a fund for Jack Hensley's daughter, Sara, at www.jackhensley.org.

Outside Hensley's suburban home, a trickle of friends came Tuesday to give condolences to his wife and daughter. One neighbor delivered food wrapped in foil.

"Jack's agenda was to help the people of Iraq," said Ken Cole, a 19-year friend.

Allawi: No Release Planned

Meanwhile, Interim Iraqi Prime Minister Ayad Allawi (search) said his government was not negotiating with the terrorists who beheaded Hensley and another American hostage, Eugene Armstrong (search), while threatening a third. Officials at the U.S. Embassy also said a high-profile prisoner and another woman would not be released immediately.

One of the demands that the kidnappers had made was for all female Iraqi prisoners to be freed. The third hostage, a Briton, is being held captive pending the same demand.

Earlier Wednesday, Justice Ministry spokesman Noori Abdul-Rahim Ibrahim said Rihab Rashid Taha (search), a top female germ-warfare scientist, would be conditionally released "on bail." He added that the decision "has nothing to do with the threat made by the kidnappers."

Taha, who became known as "Dr. Germ" (search) for helping Iraq make weapons out of anthrax, and Huda Salih Mahdi Ammash (search), a biotech researcher known as "Mrs. Anthrax" (search), are the only two Iraqi women held in American custody, according to the U.S. military.

Iraq's leader and U.S. officials moved quickly to squelch the idea that she would be freed soon. The two female scientists from Saddam's regime "are in our legal and physical custody. Legal status of these two and many others is under constant review," the spokesman said.

Representatives of the Iraqi government and U.S. coalition forces have identified a group of about 14 high-value detainees, including Taha, who may be eligible for release because they are no longer needed for questioning and do not pose a security threat, a multinational force official said on condition of anonymity.

The Iraqi government has already assented to all the names on the list, the official said. The list has gone to coalition forces and the U.S. Embassy for final approval.

The Iraqi government has also made a special request for the release of Ammash on humanitarian grounds, the official said. But because she is one of the top 55 most-wanted Iraqis on the so-called deck of cards, her case requires a Pentagon review.

"We want to make certain that there is no connection between the decision to release her with al-Zarqawi's demands," a Western official also said on condition of anonymity.

In a telephone interview with The Associated Press from New York, Allawi said his government was reviewing the status of its detainees, a process he said began three weeks ago.

Allawi insisted that the review process had nothing to do with the current hostage situation and had started weeks ago in Iraq.

"We have not been negotiating and we will not negotiate with terrorists on the release of hostages," he said in a telephone interview from New York. "No release takes place unless I authorize it."

Third Hostage in Peril

The terrorists had not set a deadline for Bigley's slaying, and it did not issue such pleading videos in the cases of the two slain American hostages. It was not known if the video posted on Wednesday was connected to earlier reports one female prisoner might be freed — reports that were quickly quashed by the United States and Allawi.

Kenneth Bigley's brother recorded a message to be broadcast on Arabic language TV station Al-Jazeera urging his captors to free him in response to the expected release of the Iraqi woman.

"They need to see it on television, they need to see females walking free," said Paul Bigley. "Hopefully they will pick this up on the media and show that they have a gram of decency in them by releasing Ken."

But Britain's Foreign Secretary Jack Straw appeared to hold out little hope for saving Bigley.

"We continue to do everything we can to secure Kenneth Bigley's safe release, but it would be idle to pretend that there's a great deal of hope," Straw told reporters in New York, where he is attending the United Nations General Assembly.

Straw stressed that Britain would not give in to the hostage takers' demands. "We cannot get into a situation, and I believe the family understand this, where we start bargaining with terrorists and kidnappers," he said.

Tawhid and Jihad, an Al Qaeda-linked group led by Abu Musab al-Zarqawi (search), claimed Tuesday to have killed Hensley, saying its demands for the release of Muslim women had not been met.

On Monday, the group released gruesome footage of the beheading of Armstrong, the first hostage of the group to be killed. His body was discovered Monday just blocks from where he lived, western officials and witnesses said, raising the possibility that the hostages never left Baghdad.

"The nation's zealous sons slaughtered the second American hostage after the end of the deadline," the statement said. It was posted on an Islamic Web site and could not immediately be verified.

Several hours passed after the initial announcement with the promised video proof failing to appear. On Monday, by contrast, the video of Armstrong's killing was posted within an hour of the initial statement claiming he was dead.

Late Tuesday, an expanded version of the statement announcing Hensley's death appeared on a different Islamic Web site and warned that Bigley, 62, would be the next to die unless all Iraqi women are released from two U.S.-controlled prisons, Abu Ghraib and Umm Qasr.

Hensley, Armstrong and Bigley were kidnapped Sept. 16 from a house that the three civil engineers, working for the construction firm Gulf Services Co., shared in an upscale Baghdad neighborhood.

Bush: Say No to Thugs, Terrorists

"Our thoughts and prayers are with the Hensley family," Scott McClellan, the White House spokesman traveling with President Bush, said Wednesday. "Their strength during a difficult time is amazing. The terrorists want to shake our will, but they will not. "

The latest beheading "shows the true barbaric nature of the enemies we face in Iraq that they would take innocent civilian life," McClellan said. "They will be defeated, they will not prevail."

President Bush took a hard line during his speech to the U.N. General Assembly in New York on Tuesday, when he said: "We will not allow these thugs and terrorists to decide your fate and to decide our fate."

Tawhid and Jihad — Arabic for "Monotheism and Holy War" — has claimed responsibility for killing at least seven hostages, including another American, Nicholas Berg (search), who was abducted in April. The group has also said it is behind a number of bombings and gun attacks.

A host of militant groups have used kidnappings and bombings as their signature weapons in a blood-soaked campaign to undermine Allawi's interim government and force the United States and its allies out of Iraq. The violence has already persuaded companies to leave Iraq, hindered foreign investment, led firms to drop out of aid projects, restricted activities to relatively safe areas and forced major expenditures on security.

More than 130 foreigners have been kidnapped in Iraq, and at least 26 of them have been killed. Many more Iraqis have also been seized in the chaos since Saddam Hussein was ousted last year, in many cases for ransom.

The Associated Press contributed to this report.