Bearded, bald and burly ex-soldier Wu Gan calls himself The Ultra Vulgar Butcher. He poses for online portraits brandishing knives in both hands that he says he'll use to "slaughter the pigs" among local officials who've done wrong.

Since 2009, he championed a confrontational approach to compel police, local officials or the courts to address alleged unfairness in China. He traveled to remote communities to shame local authorities into doing the right thing.

His stunts included putting the likeness of a local official's face on a naked mannequin and threatening to hold a funeral service for a top judge. When authorities held a fellow activist at a hotel, Wu had an open invitation for like-minded people to visit the detainee, prompting his release by jittery officials wary of a crowd.

"I don't want to see policies being dictated by hooligans who will do harm to the nation. And so we go out there to help people, with the simple hope that our action will make this country a better place to live," he said in a 2012 video he made for supporters in the event that he should ever disappear or be arrested.

That day has come. Wu was formally arrested this month, as part of a recent crackdown on a loosely allied group of more than 200 "rights-defender lawyers" and the activists associated with them. He is among dozens who remain detained and may eventually stand trial.

They are the latest group targeted by the government under President Xi Jinping as it dismantles — one by one — any group with the potential to gain enough influence to threaten the Communist Party's monopoly on power. The party also has launched campaigns since 2013 to hush influential online bloggers, and to lock up members of the New Citizens movement that had openly called for greater government accountability.

Authorities have accused the lawyers of sabotaging the country's legal system, including by arranging illegal demonstrations outside the court venues of cases they were involved with. The lawyers and activists argue that public action is sometimes necessary to get any justice at all in the largely party-controlled courts.

Wu was perhaps the highest-profile of the non-lawyer activists in this latest group, known for his knack at transforming online sentiment into on-the-ground activism. He was nominally an employee of Beijing law firm, but it was unclear whether he was paid.

Activists like Wu and the lawyers focused on individual cases instead of challenging Communist Party policy at the national level, making them a greater headache for local officials than for Beijing. But their ability to organize and bring people out on the ground apparently made authorities nervous.

"If his acts did not inspire fear in them, why are they arresting him?" said fellow activist Zhu Chengzhi.

Zhu credits Wu for his release in early 2013, when he was under house arrest in a hotel in the southern city of Shaoyang because of online activism. Wu invited fellow activists to travel there to celebrate Chinese New Year with Zhu in the hotel. That made Shaoyang officials nervous enough to let Zhu go.

"He put enough pressure on the local government that I was released on parole before the Chinese New Year," Zhu said in an interview. Otherwise, he said, "I would still be having jail meals."

Unlike China's well-educated liberal intellectuals, Wu hails from a humble, rural background in the southeastern province of Fujian. He had no more than nine years of schooling, joined the army and worked as an airport security officer after discharge.

Wu rose to fame in 2009 when he traveled to Hubei province to meet a young woman who fatally stabbed a government official who police said had made sexual advances. The high-profile case generated heated discussions online, but Wu was the first one to step away from his computer keyboard and take action by meeting with Deng Yujiao. He later persuaded her family to hire lawyers and raised money for her.

"Public attention snowballed" after that, said Human Rights Watch researcher Maya Wang, who credited Wu for Deng's eventual release. "He was the leader of that thread that connected with victims, rights lawyers, the online community, and so on."

In 2010, Wu helped mobilize 1,000 people to descend on a court in the southeastern city of Fuzhou to protest a trial over online speech.

In May 2015, after a police officer killed an unarmed but irate villager inside a train station in a northeastern Chinese city, Wu used social media to seek out an independent video of the incident, and found one in which the villager was beaten by the policeman. That widely circulated clip generated sympathy for the villager, and forced authorities to take the unusual step of releasing additional security camera footage of the incident to state media. That footage showed the villager clearly out of control, but Wu's clip had raised questions about whether the police officer had unnecessarily provoked the man.

State media have been critical of Wu and his tactics. The party-run People's Daily wrote in May that since the stabbing case, "his clown-like acts and vulgar performances have never been absent from the scene of any hot issues around the country."

"As time went on, he grew bolder, his acts more outrageous to put pressure on local governments and achieve personal gains," the paper wrote. "He even used illegal means that were degrading, and he launched vicious attacks, but he labeled all of these as unique 'performance art.'"

In 2012, when local residents in a Fujian province community were protesting what they considered an unfair seizure of their land by local officials, Wu targeted the female official most associated with the seizure. He put a likeness of her face on a naked mannequin and then uploaded photos of himself making obscene gestures with it, the People's Daily said.

Wu was arrested May 19 in the southeastern city of Nanchang. He had traveled there after defense lawyers were denied access to files in a case in which four men were serving prison time for a double murder despite a later confession from a fifth man.

Wu wanted to put pressure on the court's chief judge, Zhang Zhonghou. In social media, Wu called Zhang a rogue and said he planned to hold a mock funeral for him, order white chrysanthemums for mourning and parade a statue of him around town.

He was arrested after unfurling a banner that insulted the judge. He was later moved to the Fujian province city of Xiamen, where he faces broader charges of causing trouble and inciting to overthrow state power, though prosecutors have not released details of the case against him.

Wu could not be reached for comment. His lawyers, Li Fangping and Yan Xin, have argued that his acts are a protected form of free speech and that public officials should be subjected to a higher level of scrutiny than the public.

Zhang Weiyu, one of the lawyers representing the four men believed to have been wrongfully convicted, said they were hoping Wu's activism would "prod the authorities into doing the right thing."

"And in reality, it did help raise the profile of our case. You cannot underestimate the impact his acts have generated," the lawyer said.

Zhang Weiyu said he does not think Wu's acts were unlawful, although Wu did push the envelope.

"I really admired his courage, and I cautioned him to be more careful," he recalled. "And he told me he did not believe he was doing anything wrong, and that he knew the boundaries."