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An online video purporting to show a public execution in the Chinese countryside has reignited debate about the death penalty in a country consistently singled out by human rights groups for executing vastly more people than any other.

The video, posted to the Sina Web portal Monday evening, is shot from a ridge overlooking a field and shows a group of onlookers watching as a line of police cars drives into a field, sirens blazing. The camera zooms in to show blurry images of what appear to be police removing a figure from a van wearing a white placard around the neck. Onlookers can be heard talking casually as the figure is led into a field, made to kneel and is shot in the head.

China Real Time was unable to verify the authenticity of the video (warning: graphic content). A short line of accompanying text said the footage was originally posted online prior to November 2012 but gave no other information. Onlookers, described in the video's title as local villagers, speak a dialect found in the region of southwestern China's Guizhou province.

The video had been viewed more than 2 million times and attracted thousands of comments by Tuesday evening.

Chinese people largely support the death penalty – a Sina survey cited by state-run media put the number at 75% in 2010 -- though a number of wrongful convictions and other controversies have swelled the ranks of those who want to see it abolished or severely curtailed.

That split was evident in the two most popular comments on Sina's video site.

"Respect human rights! Oppose the death penalty!" read the most popular comment, pushed to the top with 598 likes.

"Idiot. You think those who are sentenced to death are normal people?" read the second comment, liked 570 times. "Their victims probably suffer more than they do. I resolutely oppose getting rid of the death penalty."

China doesn't publicly report execution figures, but human-rights organization Dui Hua puts the number at around 3,000 in 2012. That number is dramatically reduced from 2002, when it said China executed an estimated 12,00, but it still dwarfs reported numbers from other countries.

In its 2012 report on the death penalty, human-rights organization Amnesty International said at least 682 executions were carried out in countries other than China in 2012.

Many of the reactions to Monday's video reflected recent controversies, including one in April in which a local court overturned the death penalty for a man coerced into confessing to the murder of a woman in the eastern city of Hangzhou.

"The most important reason to get rid of the death penalty is that you can't undo the damage done to those who are wrongly convicted," wrote one commenter on the Sina video site.

Most of the criticism, however, focused not on the morality of the purported execution, but instead on the manner in which it was carried out – and on the reactions of the onlookers, many of whom can be heard talking casually and laughing before and after the shooting.

"We're still eating blood buns – listen to the sound of them laughing and chatting," wrote one commenter in a reference to "Medicine," a short story by early 20 century satirist Lu Xun in which a father feeds his son a steamed bun dipped in the blood of a recently executed criminal in the belief that it will cure his tuberculosis.

Many others were equally disturbed by the public nature of the alleged killing. Although China's recent history is littered with tales of public executions—some carried out inside stadiums in front of thousands of spectators—that practice is now illegal thanks to a provision in the Criminal Procedure Law that says death sentences should be publicly announced but not made into a public spectacle.

With worries growing that Chinese society might begin to crack under the pressure of slowing growth and a widening wealth gap, a number of observers speculated the execution was intended to send a message.

"Didn't the Supreme Court ban killing people in the street a long time ago?" lawyer Gan Yuanchun wrote on Sina's Weibo microblogging platform.

"This feels like killing the chicken to scare the monkey," wrote another. "The point is to terrorize."

The Supreme People's Court did not immediately respond to a request for comment.

-- Josh Chin. Follow him on Twitter @joshchin

[UPDATE, Aug. 15: An earlier version of this post cited a Dui Hua chart estimating China executed 13,500 people in 2002. Dui Hui has since informed China Real Time that it recently revised that estimate down to 12,000.]

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