Michael Chu, who runs a travel agency, has garnered a team of volunteers to patrol Flushing in New York every week night. Photo by Xing Xudong / China Daily

"What I am doing is beyond what lawyers can do. For example, local police do take care of the criminals, but they don't intervene with labor disputes and domestic disputes. As an example, I don't provide people with food stamps or housing; but instead I tell them where to get them and how they can get them," Chu said.

In 2007, the death of a 70-day-old infant born to Chinese immigrants living in Queens, New York, drew his attention.

The New York Times first reported that the baby suffered from a fractured skull, brain and eye injuries, two broken legs and a fractured rib. Law enforcement investigations suggested the death was "homicide by shaking and a blunt impact to the head," which led to her parents, 27-year-old Li Hangbin, 27, and 26-year-old Li Ying, 26, going to prison.

The case triggered a debate on the hard-to-spot signs of shaken baby syndrome and the role of doctors in deciphering them.

After the Chinese immigrant couple was charged with their daughter's death, Chu said they had become vulnerable targets of the American justice system.

He said the couple called him from prison. "They were nice, young people, not killers, not insane," Chu said. "And so I made up my mind. I had faith that they were innocent."

By reaching out to experts on shaken baby syndrome across the country, and compiling a medical history of the Li family, Chu was able to call attention to a genetic condition called "osteogenesis imperfect''. He even helped raise more than $50,000 that went toward legal fees and bail.

However, in early 2013, the child's father was sentenced to a maximum of 15 years in prison. His wife, who had a second child after the incident, is on parole.

"It is certainly disappointing," said Chu, who maintains that Li would do nothing to harm his baby.

Chu said that Li turned down several plea deals from the district attorney before going to trial, and that his defense was out-matched by the district attorney's office, which had a cadre of lawyers on the case and a succession of medical witnesses.

"It is really unfair," Chu said.

Chu's work to help Flushing's Chinese community has grown.

His office walls are covered with newspaper clippings and "thank you'' flags from cases in which he played a vital rule. Local reporters from Chinese media also like to hang out in his office.

"Reporters come here not only for coffee or water, they come here for story ideas. Everyone who walks into my office has something to tell. I also organize a weekly news conference here," Chu said while gesturing to the spare desks where the reporters set up base.

Though described as "elected" among "the major of the new arrivals" in Flushing by the New York Times earlier this year, Chu said he doesn't intend to go into politics.

And when it comes to the possibility of danger he could face for being such a community activist in Flushing, Chu says, "I have been very cautious. When I am alone, I have to lock the door. Actually I am thinking about buying a bullet-prove jacket."