That the May 2 shooting, in the north-eastern town of Qing'an, happened in broad daylight at a crowded train station made it resonate even more. A smattering of mass knifings and home-made bomb attacks targeting train stations last year resulted in tightened security across China's major transport hubs – and in many police carrying firearms for the first time.

In the prolonged absence of clarity and transparency, the death of Xu Chunhe, 45, prompted public outcry amid concerns that the policeman, Li Lebin, had used excessive force or had otherwise mismanaged a situation which led to an avoidable death.

Underlining an inherent distrust in the police and the country's state-controlled media, the authorities' immediate account of events – that Xu was behaving violently, tried to steal the officer's gun and even threw his young daughter to the ground in the process – was met with widespread disbelief. With each passing day, calls for police to release surveillance footage to substantiate its claims grew louder.

Conflicting reports emerged over Xu's backstory. Some said his elderly mother was a professional beggar travelling into town to beg. Others suggested he had a long-running dispute with local officials and was planning to petition at higher levels. Either way it was his belief that he would be intercepted by police that set him off.

At its core, the narrative developing was a familiar one in China – police acting with impunity against those on the lowest rung of society.

Xu was fast becoming a cause celebre with rights lawyers wondering if this could prove a watershed moment in police accountability, much in the same vein as the United States in Ferguson and in Baltimore.

But the outrage at the shooting – largely confined to social media, unlike Baltimore or Ferguson – also manifested itself in another unexpected yet distinctly Chinese outcome.

Seemingly stirring a groundswell of anger toward authority more broadly, locals reported cases of corruption among local officials en masse. Ten days after the shooting, Qing'an party secretary Dong Guosheng was stood down, and at least 10 other officials are being investigated after public tip-offs.

As one online comment put it: "one gunshot was fired, but numerous bodies are laid on the floor".

Public anger grew on Thursday, almost two weeks after the shooting. Chinese police cleared Mr Li of any wrongdoing, finding that Mr Li had shot Xu "as part of his duty" and "did not violate protocol".

Xu had "allegedly initiated the assault on [Mr Li] and continued the attack despite multiple warnings before the police officer shot him", police said.

An autopsy showed Xu was heavily intoxicated at the time.

Coinciding with the police announcement, state broadcaster CCTV released security camera footage which, while edited, did show an agitated Xu clashing aggressively with Mr Li. It also showed Xu throwing his young daughter violently to the ground and briefly using his 81-year-old mother as a human shield against a baton-wielding Mr Li.

While the released footage has been effective in swinging public sentiment against Xu, many still question why the policeman didn't call for backup, or whether he gave sufficient warning after drawing his gun.

Not publishing the original video in full, prominent lawyer Zhang Xuezhong said, "just shows they are hiding things", adding that it was an obvious conflict of interest that it was the railway police, and not an independent body, that investigated and cleared Mr Li.

The Xu family's lawyer, Xie Yanyi, said CCTV had edited the footage to "demonise his client's morals". Mr Xie said while Xu did hit the police officer and knock his child to the ground, he was no threat to anyone besides the police.

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