And yet, as many as 70 per cent of respondents in a an internet survey expressed sympathy with Li's frustrations and cheered the fatal stabbing.

The tragedy demonstrates the growing tensions between patients and doctors on the mainland. There has been a spate of cases in which dissatisfied, frustrated and angry patients or their families have attacked doctors.

Although official data is unavailable, reports in the state media say that in 2010 there were more than 17,000 "violent incidents" at health-care facilities nationwide, a 70 per cent increase from 2004.

Added to the problems besetting the public health-care system is doctors' fear for their safety and that of their families. Already doctors have begun to joke that they will not sit with their back to the door - that's how the killer found 28-year-old Wang Hao when he attacked him.

The problems in the health-care system look set to grow as the violence of patients deters elite students from studying medicine. Despite the government's huge investments in public health-care over the past three years, the doctor-patient relationship has continued to deteriorate.

Doctors are overworked and underpaid, and many promote sales of expensive drugs or charge extra for services to make more money. As a result, some patients may be faced with high medical expenses, brief consultations and often poor-quality care.

Wang Hao's killer, Li Mengnan , was sentenced in the Harbin Intermediate People's Court in September. In addition to his life term, he was also ordered to pay 680,000 yuan (HK$838,000) to Wang Hao's family and the three injured doctors. Li has since filed an appeal.

Meanwhile, relatives and friends insist on staying with Wang Dongqing and his wife - who has carried a picture of her son with her since his death seven months ago - for fear their grief will drive them to suicide.

Li, a young migrant worker, has admitted his actions were wrong and said the knife rampage was an impulsive reaction after a nightmare that had lasted more than a year, reported.

It began in September 2010, when his grandfather, himself in poor health after surgery for stomach cancer, took him to the First Affiliated Hospital - one of the largest health centres in the northeast and more than 700 kilometres from their hometown, Hulunbeir in Inner Mongolia. Li was suffering from pains in both his legs that were so bad he had been forced to quit his job at a public bathhouse.

He first went to the orthopaedics department, which directed Li to the rheumatology department. There, a senior doctor said his problem was not within the department's field of expertise and sent him back to the orthopaedic department, where he was given a painkilling injection.

About seven months later he returned to the hospital and this time he was diagnosed with ankylosing spondylitis, a chronic inflammatory disease of the spine. A doctor from the rheumatology department, who Li later described as arrogant, suggested prescribing Remicade, an imported medicine costing him 6,240 yuan.

After receiving a second painkilling shot in May last year, he developed a fever and a week later he was diagnosed with tuberculosis. He was advised to return to his hometown for more treatment.

Three more journeys to the hospital in Harbin followed, where he was told he had to continue his TB medication before anything could be done about his other condition.

It was on the last of these visits that Li snapped, buying a fruit knife in the hospital kiosk before storming into the doctors' meeting room and launching his attack. "I was angry at that time. My grandfather and I had travelled a long distance a number of times and had spent a lot of money and effort but the doctors were just deliberately making things difficult. I hate doctors," the newspaper quoted Li as saying.

Beijing-based rights lawyer Li Fangping , who is representing Li Mengnan without charge, told the that his client had suffered from a misdiagnosis at the Harbin hospital.

"In the first two check-ups they didn't discover TB," he said. "They prescribed Remicade, but later refused to administer the medicine. It's contradictory."

Li Chunming , uncle of Li Mengnan and like him a penniless migrant worker, said they had decided to appeal against the verdict in the hope that the court would take into consideration that the teenager had turned himself in to police and that the hospital had made mistakes in its diagnosis.

"The sole valuable asset in my family is our bungalow. If Wang Hao's family likes it, we can give it to them and it's worth about 20,000 yuan," Li Chunming said, adding that he and his sister were the family's only breadwinners and that they earned little.

He added: "Not long ago my nephew's lawyer met him in prison and found out that he hasn't been given him any medication and that his problems have deteriorated. It's inhumane.

"We are helpless because we are an impoverished family and we don't have any money or any connections with powerful officials to persuade the prison to give Mengnan drugs. We are quite worried that he will become paralysed or even die in prison," Li Chungming said.

Back in Chifeng, Wang Dongqing insists the life sentence was just revenge for his son's killing and hopes it can help to create a safer working environment for doctors.

However, Ma Jin , dean of public health of Shanghai Jiaotong University, said mainland patients had high expectations of medical services and simply refused to accept, after paying steep hospital bills, that their diseases could not be cured.

Xia Xueluan , a sociologist at Peking University, sees Wang Hao's murder as the responsibility of a society that created a "problematic minor" who lacked a decent education.

"There should be a support system in our communities and schools for these children," he said. "Without such aid, it's possible that there will be a another Li Mengnan who kills innocent people after years of feeling frustrated in society."