(AP) -- At one moment, the Chinese urologist seemed to be at the height of his career: He had invented a surgical procedure to help patients overcome incontinence and was training doctors in America and elsewhere. The next, Dr. Xiao Chuanguo was in handcuffs, confessing that he'd hired thugs to attack two persistent critics who called him a fraud.
The scandal has shocked the public and prompted calls for better regulation of medical research in China, where such fraud and misconduct are widespread. Yet, Xiao's case is not such a clear-cut illustration of the problem. More than 30 urologists from the United States, Canada, France, India and other countries issued a letter in support of the U.S.-trained surgeon after his arrest late last month.
In China, several former patients have complained about severe side effects, including a worsening of their mobility. The respected Southern Weekly newspaper said in an analysis that poor regulation led to Xiao "treating patients as if they were voluntary lab mice."
Last week, a Beijing court sentenced the 54-year-old doctor to five-and-a-half months in detention for his role in the attacks. Xiao, in police custody, could not be reached for comment.
Some American doctors consider his technique experimental but promising, and two U.S. hospitals are carrying out studies on a small number of volunteers, mostly children. Others, though, are skeptical, particularly of his claims of an 85 percent success rate. The surgery is meant to help people who cannot control their bladders because of a paralyzing accident or spina bifida, a birth defect.
The procedure involves rerouting nerves in the spine, connecting one that would normally squeeze the bladder with one that functions in the thigh. If they fuse, scratching the thigh can signal the bladder to empty.
"Most of the pediatric urologists in the United States were very cynical about his reports," said Dr. Eric Kurzrock, chief of pediatric urology at the University of California Davis Children's Hospital in Sacramento, California. "Nobody ever believed there was an 85 percent success rate, you know, and when you looked at his reports they were very short on details."
In China, Xiao forged ahead with the surgery on hundreds of patients, according to media reports. Now, some are saying he exaggerated the chance of success and that the surgery left them worse off.
Whether or not he is guilty of fraud or an ethical lapse, his case highlights the unregulated nature of research in China, with few protections for patients.
"It's no secret that the Chinese medical space is the Wild West," said Cong Cao, a researcher at the State University of New York who has written two books on China's science and innovation.
One man, Fang Shimin, has emerged as an unofficial sheriff, unearthing examples of scientific fraud and posting them on his website.
He took on Xiao, and the two ended up in a long-running feud. Separately, investigative journalist Fang Xuanchang, no relation to the other Fang, also started writing critical pieces about Xiao.
The stakes are high for Xiao, who once told reporters his procedure should win him a Nobel Prize and has said that becoming a target of the two Fangs cost him a seat in the prestigious Chinese Academy of Sciences.
In June, two men attacked the journalist Fang with metal pipes, leaving a deep gash on his head. Two months later, the other Fang was attacked with a chemical spray and a hammer, escaping with minor injuries.
Police arrested Xiao after he returned from training doctors in Argentina. In a videotaped interrogation, the doctor said he paid a distant relative 100,000 yuan ($15,000) to hire two men "just to give them black eyes and swollen faces ... but not to do any permanent damage.
"Nothing else would solve the problem except beating him up," he said, referring to Fang Shimin, the reporter.
Half a dozen patients and family members protested outside his trial, saying they represented 200 patients who were duped by Xiao into thinking the 30,000 yuan ($4,500) procedure had an 85 percent success rate.
"We need an explanation. We need justice," said Qu Binbin, a 29-year-old man in a wheelchair who said he was able to get around without crutches before having the surgery three years ago.
Supporters of the doctor also showed up. Guo Yuling, a 19-year-old college student, said he constantly wet his pants for the first 13 years of his life before Xiao's surgery.
Two former patients are suing Xiao for false advertisement, and more lawsuits are planned, said Peng Jian, a human rights lawyer who said he has documented 150 cases in which the surgery had no benefit or left patients worse off.
So far, the scandal has not derailed plans to continue studies in the U.S.
Researchers at William Beaumont Hospital in Royal Oak, Michigan, reported mixed results - and some side effects - from a pilot study of nine spina bifida patients. By early next year, they plan to begin a five-year clinical trial funded by $2.3 million from the National Institutes of Health.
Dr. Kenneth Peters, the hospital's head of urology, said he ensures that patients are fully aware the surgery is experimental and carries serious risks.
"Dr. Xiao has been nothing but in our experience an incredible gentleman, scientist and a very good colleague," said Peters, one of those who signed the letter in Xiao's support.
A separate three-year study on eight children is under way at All Children's Hospital in St. Petersburg, Florida.
Explore further: That neat and tidy map of tastes on the tongue you learned in school is all wrong