She looks like any other disgruntled young person. Arms tightly crossed, mouth twisted in contempt, she could be letting off steam about parents, school, or boyfriends.

But when 21-year-old Gao Qianhui sat down in front her webcam last month, she had far more important issues on her mind. Upset that the three-day mourning period for the 80,000 victims of the earthquake in southwest China had disrupted her television viewing schedule, she launched into a five-minute spew of vitriol and then posted the video online.

"I turn on the TV and see injured people, corpses, rotten bodies... I don’t want to watch these things. I have no choice.” Ms Gao sighed: “Come on, how many of you died? Just a few, right? There are so many people in China anyway.”

Within hours, Ms Gao had become the latest victim of a human flesh search engine, where Chinese netizens become cyber-vigilantes and online communities turn into the world’s largest lynch mobs.

Using the vast human power behind the Chinese web, every detail of Ms Gao’s life, from her home and work address in Liaoning province, north east China, to the fact that her parents were divorced, was dug up and published on hundreds of forums and chatrooms.

“Now humiliate her,” ordered one internet user, Yang Zhiyan.

The outraged reaction to the video drew the attention of the local police and they detained Ms Gao the next day. They did not make clear what law she was alleged to have broken.

Ms Gao was the fifth person to be targeted by a human flesh search engine since the 8.0-magnitude earthquake ripped through Sichuan province on May 12.

On the day of the quake, three high school students in the provincial capital, Chengdu, made a spoof news cast as they were evacuated from their classrooms, joking that they hoped their school would collapse and they would not have to go back. A few days later, shaky and tearful after the harassment of hundreds of netizens, the same students filmed an apology: “We really didn’t have bad intentions. We really do love our country…Thank you to all of our internet friends for alerting us to our mistake and for criticizing us.”

In Hong Kong, a schoolgirl was also forced to publicly apologise after writing on her blog that she “had no feelings for Sichuan, no sadness or sympathy”. The human flesh search engine discovered that she attended an elite school and contacted the head teacher. The girl was threatened with expulsion and forced to shut down her blog.

With their vast number of participants and angry nature, these witch hunts for a digital age are a uniquely Chinese phenomenon.

Xujun Eberlein, the Chinese-American writer and observer, said: “China’s population makes it easy to mobilize a large number of netizens to participate in such a search, especially considering that there are many smart and reasonably well-educated people in China who are intellectually underemployed."

She added: “I think there is some pleasure in the idea of making information available when there has been such significant suppression of both thoughts and facts over the previous five decades.”

According to Ms Eberlein, the term “human flesh search engine”, a literal translation of the Chinese, was first coined in 2001 when an entertainment website asked users to track down film and music trivia.

With 210 million Chinese wired up to the internet, it was a powerful concept. It quickly caught on and came to be used as a tool to punish the perpetrators of extra-marital affairs, domestic violence and morality crimes.

In one infamous case in 2006, a woman now dubbed “the kitten killer of Hangzhou” posted a video of herself stomping a kitten to death with her stiletto heels. China’s netizens erupted with rage and hundreds of amateur sleuths traced the video to Hangzhou, a city south of Shanghai. They discovered the woman’s name and that she had recently purchased a pair of high-heeled shoes on eBay. They attacked her until she apologized on a local government website and lost her job.

“Righteousness is one of the five virtues in the Confucian tradition,” Ms Eberlein said. “With the convenience of the internet, and in the case of non-responsive law, the righteous people took matters into their own hands.”

But 2008 has seen these search engines take on a new role. As Tibet erupted and the Olympic torch relay was hampered by violent international protests, they have been increasingly driven by a potent wave of Chinese nationalist sentiment.

In April, Grace Wang, a Chinese student at Duke University in America, faced the wrath of the online mob when a photograph of her writing “Free Tibet” on a classmate’s back during a campus vigil appeared on a Chinese forum. “Traitor to your country” had been printed over the image.

She insisted that she had been trying to act as a mediator and had only written the slogan after the student agreed to talk with pro-China demonstrators, also gathered on the campus.

But the story of the young Chinese women who had swapped sides roared through the Chinese web with unstoppable momentum.

Ms Wang’s Chinese name, Chinese identification number and contact details in America were tracked down and posted across the internet. She received hate mail and threats that if ever she returned to China, she would be “chopped into 10,000 pieces”. Her parents’ address in China was published and they were forced to go into hiding.

Tibetans have also been targeted. After 44-year-old Lobsang Gendun was photographed protesting at the Olympic torch relay in London, Paris and San Francisco, the human flesh search engine whirred into action.

With huge overseas communities, it took just a couple of hours for Chinese web users to collate the pieces of Mr Gendun’s life – replete with Google satellite map and photos of his American home.

“I suggest assassination,” wrote one poster. “Execution by shooting,” said another. No, no, insisted yet another: “Use China’s most ancient form of execution – dismember him.”

In an unfortunate case of mistaken identity, it turned out there was another exiled Tibetan called Lobsang Gendun living in Utah. Since the targeting of his namesake began, Mr Gendun, a self-proclaimed “Olympic supporter”, has received hundreds of aggressive emails and telephone calls.

“Yes, we curse him to death and we are eager to see him go to Hell,” a participant in the hate campaign against Mr Gendun – it did not seem to matter which one – said. “But do you see us pouring petrol round his house? We are just expressing our rage.”

Yang Zhiyan, the chief instigator of the backlash against 21-year-old Gao Qianhui, was also quick to dismiss any notion of wrong doing. “She just had to be stopped,” the 27-year-old said simply. “In the face of a catastrophe, we Chinese have to be of one heart.

“Gao Qianhui publicly defamed the State Council’s announcement of a national mourning period through the fastest and most effective avenue possible [the internet] and she should be dealt with according to the laws on public order.”

He added, proudly: “It was the great netizens who alerted the police and gave them her details to arrest her.”

Video translation- what Gao Qianhui said:

"I turn on the TV and see injured people, corpses, rotten bodies, all these crazy things. I don’t want to watch these things. I have no choice. Look, now the entire internet is black-and-white and without colour. Do you think we're all colourblind like you? Have your eyes been blasted with so much rubble that you can't see any colour now?

"You guys, if you're hit by the rubble just go suffer by yourself quietly...What are you screaming for? What rescue are you asking for? Not that I'm blaming you...you guys in Sichuan are in a terrible place in China. They say the Indian plate is crashing into you. Don't you think you guys deserve it?

"I don't think this earthquake was strong enough. If only it had just been a bit stronger to flip you guys over. Today we're mourning for you. Tomorrow we're donating money to you. May 21 is such a great day. Lots of people want to get married. And now we have to mourn for you. Do you think those couples should get married or not? What a spoilsport! May 20, May 21, such auspicious days, now all spent mourning for you. Come on, how many of you died? Just a few, right? There are so many people in China anyway.

"F***...You're driving everyone crazy...What are you doing! Do you think you're all that goodlooking? Which part of your body is that precious? People are giving you cash and giving you food. And you guys are doing nothing? These few days, it's just impossible to go anywhere without being reminded of you silly c****...Everywhere I go people are saying, 'Argh, aftershocks in Sichuan again, this and that...'

"As for that old lady who's been lying there for over 100 hours? Why haven't you died yet? Are you a mummy?

"F***... the earthquake might as well kill you guys... All you have given us are catastrophes... All your children are jinxes."

Related Human flesh search engines stories:

Human Flesh Search: Vigilantes of the Chinese Internet

Human Flesh Search Engine helps us know more about Chinese road killer

The Unique Chinese Internet Culture - Human Flesh Search Engine