BEIJING, July 3  -- Tian Hao was 16 when he first saw the body of a drug addict.

He had lied about his age to enlist in the army. Walking past a detention center in a military base in Yunnan Province, he saw the body being carried out: shriveled, with no skin on the face, the skull and teeth exposed, the hands and feet the color of dust.

"At that moment, my revulsion for drugs crystallized," says Tian.

Tian served in the narcotics division of the Armed Police at the border between Yunnan and Burma from 2006 to 2010. Four years after leaving the squad, he still recalls the rank smell and twisted faces of the drug addicts.

He is now a commentator on an Internet forum "Zhihu", where he has more than 70,000 followers. He answers questions such as: "What should I do if my roommate takes drugs?" and "How do the police catch drug smugglers?"

Tian tells stories about drug smuggling investigations without revealing real names and details of the operations or the investigative methods.

"So little information about drugs on the Internet is reliable," Tian says. "People don't like to read essays so I started chatting online. When I see comments that I disagree with, I speak out."

Tian had a rough childhood in a small village in Chuzhou city, east China's Anhui Province. His father drank and beat his mother, and died when Tian was nine. His mother put all her faith in Tian, but the boy hated school.

He thought the military was cool, so joined the army as soon as he graduated from middle school. After a year of basic training, when he developed outstanding shooting skills, Tian joined the border narcotics division.

Tian spent a further three months of training at a border checkpoint in Yunnan, where he witnessed all kinds of drug trafficking.

He had seen naked pregnant women who hid drugs internally. They were impoverished people from an ethnic minority in Sichuan. Some of them gave birth and died while carrying drugs.

"It is very difficult to arrest people for possessing small amounts, or to arrest pregnant women and ethnic minorities," says Tian. These trafficking mechanisms were stopped in an operation in 2007.

The offers of large bribes were constant. Tian's monthly salary was 300 yuan (48 U.S. dollars), but the drug dealers offered six-figure sums from suitcases of cash in exchange for their freedom when they were caught.

He understood why the first year of training had been so tough.

"The training not only shaped our bodies, but also our core values," he says. "We walked a line between good and evil; if not for the strenuous training, we might have succumbed."

Even so, sometimes the military gamekeepers turned poachers. Tian once saw his former outdoor survival skills instructor in the mountains, and realized he was trafficking drugs.

"I hid behind a rock. I could not aim my gun at my teacher," he recalls.

Tian fired into the air and the ex-soldier pulled out a gun and fired back. Bullets zipped around Tian's feet, but he stayed behind the rock and held his fire. After the man had run out of bullets, Tian showed himself and pointed his gun at the man's head.

The panic in the veteran's eyes faded when he saw Tian. He lowered his head and neither of them spoke. Tian escorted his teacher to the car in silence.

"Tian Hao, you were my best cadet. I never imagined I would be arrested by you," the man said.

"I am not sure what happened to him," Tian says. "But we found 6,000 grams of heroin on him - I can't imagine he survived that."

Off duty Tian would sometimes visit drug addicts' families. "I never saw a rehabilitated drug addict who could really stay off of drugs during my five years in Yunnan," he says.

The essential condition for rehabilitation is a drug-free environment, which is impossible near the border.

The narcotics team suggested everyone write a will. Tian rewrote his frequently.

The first comrade he lost was a veteran soldier who was due to go home four months later. He had been chasing a suspect who jumped off a 20-meter-high bridge into a river. The soldier jumped after him.

When the old soldier's body was pulled out of the water, Tian thought: "He told me not to jump into rivers, but he did it himself."

The soldier's family came and cried beside the body. Tian wondered if one day, it would be his family.

He kept his work secret from his family - until his mother saw him on the television news one day. She became depressed and urged him to leave the narcotics department.

Tian retired, but he had few academic qualifications or social survival skills. He works a few part time jobs and stays with his mother.

His fans on "Zhihu" brighten up his life. Publishers have asked him to adapt his comments into a book.

"Drug addicts and drug traffickers have every reason to take drugs," he says. "I would like to use my story to help people stay away from them."