Evidence collected by a young London-based organization called Human Rights Investigations indicates that when Arizona GOP Sen. John McCain went to Benghazi in April to express his support for Libyan rebels, he visited the site at which the rebels publicly beheaded an alleged pro-Gaddafi “mercenary” only weeks before.

Shortly after the February outbreak of the rebellion against the now-deposed Libyan leader Muammar Gaddafi, videos began to emerge showing gruesome atrocities committed by rebel forces in the parts of Libya under their control. The horrific abuse was most frequently directed at black Africans and dark-skinned Libyans, adding a racial component to the rebels’ actions.

Documented atrocities included lynchings, a summary execution of a group of up to 22 prisoners, and — in perhaps the most harrowing video clip distributed online — a public beheading.

In the video, the beheading victim can be seen suspended upside down in front of a burnt-out building. A crowd of hundreds is gathered around to watch; many of the spectators are filming the proceedings on mobile phones.

As one of the rebels begins sawing at the already blood-soaked man’s neck with a long knife, cries of “Allahu Akbar!” ring out. Like countless black African migrants and dark-skinned Libyans, the beheaded man appears to have been accused by the rebels of being a pro-Gaddafi “mercenary.” The Dutch public broadcasting service NOS reported that some in the crowd shouted “He looks like he’s [black] African!”

(The Benghazi beheading video can be viewed here. Viewer discretion is strongly advised.)

The video in question first emerged online in late March. In an April 4 report, NOS identified the location as the central square in the rebel capital of Benghazi. The burnt-out building has since been identified in news agency photos as the city’s main courthouse.

In the early days of the rebellion, rebels are known to have set fire to police stations, courthouses and other public buildings associated with the Gaddafi regime. And the rebel leaders were reported to have initially established their impromptu headquarters — including their media center for foreign journalists — in the same burnt-out Benghazi courthouse.

Traditional American media have ignored the evidence of atrocities committed by the Libyan rebels. But on April 20 Pajamas Media published a discussion of rebel atrocity videos with links to several examples, including the Benghazi beheading video.

Two days later Arizona senator John McCain, the 2008 Republican presidential candidate, made a surprise visit to Benghazi in order to publicly call for stepped-up American support of the rebellion. McCain spoke glowingly of the rebels and their cause, even saying of the Libyan rebels: “They are my heroes.”

While he was in Libya, McCain’s hosts took him on a tour of downtown Benghazi, including its central “Freedom Square.”

CNN footage of the April 22 tour shows McCain walking past the location of the gruesome public decapitation. The discovery was made by the London-based Human Rights Investigations, which has attempted to publicize vicious treatment of black Africans and dark-skinned Libyans in rebel-controlled territories.

In the CNN segment, McCain tells a rebel spokesperson, “The American people support you very strongly, and we know it’s necessary to help as much as we can.”

One minute and twenty seconds into the CNN report, McCain is seen walking past the building where the beheading took place, accompanied by Abdul Hafez Ghoga, vice-chairman of the Libyan rebels’ National Transitional Council.

Members of the group walking with McCain wave American flags, and shouts of “Allahu Akbar!” ring out as a smiling McCain walks by the site of the beheading.

In his April 22 press release, Sen. McCain praised the Libyan rebellion as “a powerful and hopeful example of what a free Libya could be — a place where the dignity and the desires of all people for freedom and opportunity are respected.”

“We need to increase our support,” McCain’s statement concluded, “so that the Libyan people can achieve the only satisfactory outcome to this mass protest for universal rights: the end of Qaddafi’s rule and the beginning of a peaceful and inclusive transition to democracy that will benefit all Libyans.”