Area relatives of a man being held hostage in Iraq waited for word about him Saturday as militants threatened to decapitate him, another American and a Briton unless demands were met within 48 hours.

Frank Armstrong said Saturday in a brief telephone interview that the FBI told him about his brother Eugene Armstrong's abduction this week. He said Eugene Armstrong (search) grew up in this south central Michigan community, but declined to discuss other details.

"This has been a big shock," Frank Armstrong said.

The threat against the hostages came in a video purportedly from a militant group linked to Al Qaeda (search) that showed Eugene Armstrong, fellow American Jack Hensley and Briton Kenneth Bigley, the first word of their fate since the three construction workers were abducted from their Baghdad office two days ago.

Minnta Davis, a cousin who lives in nearby Jonesville, said Eugene Armstrong's work in construction took him around the world and he had been living in Thailand with his wife before traveling to Iraq. Davis said she recognized him in the video, which was rebroadcast on U.S. television.

"We only know what they're showing on television," Davis said. "We don't really know anything. It's kind of hard to say what you don't know. We just know there are just a lot of prayers for him."

Davis said Eugene Armstrong moved from the Hillsdale (search) area around 1990. Hillsdale, a city of about 8,200 near the state's border with Indiana and Ohio, is located about 100 miles southwest of Detroit.

In the hostage video, posted on a Web site known for its Islamic militant content, kidnappers purporting to belong to Tawhid and Jihad — a group led by Jordanian militant Abu Musab al-Zarqawi (search) — demanded that Iraqi women detained at two American-controlled prisons here are freed within 48 hours or the captives will be beheaded. A U.S. military official said two women are in U.S. custody.

The footage showed the three hostages sitting on the floor, blindfolded but apparently unharmed. Each identified himself and said, "My job consists of installing and furnishing camps at Taji base," referring to a U.S. base 15 miles north of Baghdad.

"God's soldiers from Tawhid and Jihad were able to abduct three infidels of God's enemies in Baghdad," said a masked militant dressed in black, standing behind the men as he read from a statement.

"They offer logistic support to American troops in Iraq, as was shown from investigation and the documents seized with them," he said.

If their demand is not met, the speaker warned, "by the name of God, these three hostages will get nothing from us except their throats slit and necks chopped, so they will serve as an example."