BEIJING -- We met on the empty floor above a restaurant on the outskirts of Beijing – far away from the prying eyes of authorities. Or so we thought.

Gathered were more than a dozen former police officers who had become targets of authorities after accusing local leaders of corruption and abuse. During previous reporting on China’s police and courts, we had heard of this strange, tragic phenomenon – former officers being hunted by the very system they once upheld – and hoped to write a story about them.

Before meeting, however, members of the “Wronged Officers” group insisted on extensive precautions. As ex-cops, they were well-aware of the smothering capabilities of China’s surveillance state. Many lived under constant government surveillance and were detained whenever they try to leave their home towns to bring their complaints to Beijing.

Most had been beaten at some point and told to stop spreading their allegations.

So that day in the restaurant, before anyone could say too much, the ex-cops, one-by-one, turned off their cellphones and took out the batteries – to stop authorities from tracking or listening to them – and we did the same.

Over the next few days, as two of us from The Post, along with a veteran freelance photographer, interviewed individual members in the rundown village where they now lived, the others manned lookout points for authorities on nearby street corners. Every so often, we'd move to a new home – wary of lingering too long in one place – and the perimeter of lookouts would move with us.

“We know all their tricks,” said Liu Ming, one of the group’s chief strategists for evading authorities.

It was a role Liu fell into naturally from experience in his former police job before he was fired in leading squads of officers to hunt down petitioners.

And yet – despite such painstaking, seemingly paranoid precautions on their part and ours – just days after our interviews, Liu and another former officer we met, named Zhuo Cong, were arrested in retaliation for our secret interviews.

Both now face possible prosecution and prison time.

As a journalist, you experience incredible pangs of guilt whenever a source suffers as a result of your reporting. You think about what went wrong, what you could have done differently.

In this case, it wasn’t for lack of precautions, nor because of any particular secret we touched on. (Everything that Liu and Zhuo told us were things both had complained about for years loudly and publicly in their petitioning.) Instead, what got them in trouble was the fact that we had met at all.

It has now been weeks since authorities took Liu and Zhuo away. Other members of the "Wronged Officers" group have scrambled to find lawyers for both. Many lawyers in Liu’s home town of Huainan have refused to take his case, supporters said, fearing the local authorities who arrested Liu.

On the night after Liu returned from Beijing to Huainan, five officers from the Huainan Police burst into his home and pressed him to the floor, according to Liu's supporters. Days later, Liu was formally arrested under criminal suspicion of “stirring up trouble."

According to one friend who helped find Liu's current lawyer, police also accused Liu of "leaking state secrets" because of his interview with us – a charge that human rights experts say is frequently and flagrantly used in China to silence dissenting voices.

Zhuo – a former court officer from Dangshan County in Anhui province who says he began petitioning because he didn’t get a fair salary and was later fired for that petitioning – was also arrested on suspicion of "stirring up trouble," according to other members of the “Wronged Officer” group.

Dangshan police, who searched Zhuo’s room in the petition village outside Beijing, told others present that Zhuo had done two things wrong: Agreeing to an interview with foreign media and traveling to Tianjin City recently to support a friend whose home had been demolished by local authorities.

Neither police department responded to calls for comment.

Both Liu and Zhuo were painfully aware of the dangers of speaking out.

This year alone, Liu had already been detained seven times by police while petitioning in Beijing and dragged back to his home town. He recounted being beaten during one instance until he bled from his head and repeatedly lost consciousness as hired thugs drove him back to his home province of Anhui.

This, however, is the first time that such detention has led to formal arrest and criminal charges for Liu.

In our interviews before his arrest, Liu had explained why he felt a need to speak out.

“The petition system is a lie,” he said, referring to the pseudo-legal structure set up by China's leaders to receive complaints against the government. “It leaves us nowhere to make our voice heard. … Chinese media do not want to listen to our stories. Even when Chinese reporters are interested, they dare not write about it.”

Liu said he became a petitioner in 2008 after he was fired for making overly frank remarks that offended his superiors.

He recalled how years of frustration eventually led him to publicly air his complaints against the government in Tiananmen Square, a move he knew would result in detention.

“I knew it was a trap, but I went anyway,” he said. “I wanted to show others that petitioning doesn’t work.”

He said all his fruitless petitioning has led him to realize that no one in government cares about cases like his. “I realize now that the problem doesn’t lie with any individual; the problem is the petition and legal system itself.”

Gu Jinglu contributed to this report.