Until a few weeks ago, Deng Yujiao was an unknown 21-year-old worker in a Chinese provincial town: one of millions quietly scraping a living. Now she is an unwilling hero to tens of thousands of ­compatriots after stabbing to death an official who she says tried to rape her when she rejected his advances.

Comments on the killing have ­inundated blogs and bulletin boards. Deng's case – and its handling – has become emblematic of the struggle of ordinary people against abusive officials.

The message was spelled out in a ­protest at a Beijing university this week in which a gagged female student bound in sheets was shown surrounded by the words: "Anyone could become a Deng Yujiao."

Each twist in the investigation has aroused fresh sympathy for Deng, from the claim that the dead man hit her with a wad of cash when she refused to have sex with him to the allegation that police tried to label her mentally ill and that her mother was pressed to fire her lawyers.

The rancour has spread so fast on the internet that authorities appear to be pushing the Chinese media, which have ­covered the case extensively, to stop reporting it. Deng was working in a ­karaoke and leisure centre in Badong, central China, on 10 May when two officials demanded "special services" – a euphemism for sex – according to initial reports from the local authorities. After a brief ­struggle, she stabbed to death one of the men, Deng Guida, 44, the director of the area's ­business promotion office, and injured his colleague. ­According to Deng's account, obtained by the ­Southern Metropolis Daily, prostitution was ­common at the centre.

When she told the men she was not ­selling sex, Deng Guida responded: "Aren't you all the same? You are a prostitute but you still want to have a good reputation." Hitting her repeatedly with a wad of ­banknotes, he said: "Don't you want money? Would you believe if I am going to beat you to death with money today?"

Deng said she pulled out a knife after the men repeatedly dragged her back as she tried to leave. As Deng Guida pushed her on to a sofa, she lashed out with the blade. She then called the police to tell them Deng Guida was dying and waited for them to arrive.

Supporters say any punishment she receives should be mild because she was acting in self defence, but fear that she could face murder charges.

Police said they had found ­anti-depressants in Deng's bag and initially committed her to a mental hospital. A later police statement also toned down allegations about the dead man's behaviour and claimed Deng had stabbed him with a fruit knife, rather than with a pedicure knife, which would have been readily available at the leisure centre. Her backers fear that is intended to imply that the act was in some way premeditated.

Officials in Badong have promised Deng a fair hearing. They refused to comment when contacted by the Guardian.