A video posted Monday on a web site showed the beheading of a man identified as American construction contractor Eugene Armstrong, according to an AP report carried by NBC's web site.

NBC reported that the nine-minute tape, the authenticity of which could not be verified, showed a sobbing man, blindfolded and wearing an orange jumpsuit while a militant behind him reads a statement.

Armstrong, fellow American Jack Hensley and Briton Kenneth Bigley, were kidnapped Thursday from their Baghdad home.

The voice of the militant on the tape sounded like past recordings attributed to terror suspect Abu Musab al-Zarqawi, whose Tawhid and Jihad group claimed responsibility for the kidnappings, the report claimed.

The video surfaced after the expiration of a 48-hour deadline set by the group in an earlier statement. The militants had demanded the release of all detained women Iraqi prisoners.

Earlier, NBC reported, a contributor to the Islamic website using the pseudonym Abu Maysara al-Iraqi put up this posting: "The commander Abu Musab al-Zarqawi... today slaughtered the first American hostage ... the group will carry out the slaughter of the others next ... We will provide you with film showing the slaughter soon." Al Iraqi has put up past statements signed in the name of Tawhid and Jihad, the militant group led by Abu Musab al-Zarqawi.

Hensley's wife Pat, had earlier spoken on ABC's 'Good Morning America', apparently ignoring requests that she not speak to the media, seeking her husband's safe return. She told ABC that her husband's optimism had waned in the week before the kidnapping after his security guards either did not show up for work or used any excuse to leave.

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