The police forced the man to kneel on the ground and pumped a bullet into his head. The man tried to stand up, but was finally killed with another shot.

Yang said he remembers being very frightened. The last miserable smile from the farmer is an indelible memory stuck in Yang's head and encouraged him to create a more humane way of executing criminals.

When the invention program came up in 1998, Yang predicted a big market for injections that required more than 1,000 injection pumps, with more than 300 intermediate courts in the country eligible to implement capital punishment.

Yang and his team created the first high-speed injection pump in 2000 and it soon began to be used across China. A government policy does not allow the number of executions to be released.

Yang, however, believes his invention hasn't performed up to his expectations.

"Our goal was to be able to end life within 30 seconds absolutely painlessly," he said. "But the program did not get enough support later on, so the outcome was still far from our goal."

He also said frequent changes in local governments "have had a significant influence on the program's consistency".

"As a businessman, my creation did not provide me with many benefits," he said. "Actually, I have lost a lot of money in this line of work. We stopped producing new equipment four years ago because the more equipment we sold, the more money we lost in the business. We currently only provide maintenance service for the already sold injection pumps."

Though he refused to talk in detail about his invention and its repercussions, he mentioned that some local governments in less developed areas are not able to pay for his device, one of the downsides to his business.

"One set of lethal-injection equipment costs more than 200,000 yuan ($29,000), which is much higher than the cost of execution by shooting," said Xu Jiusheng, a professor at the China University of Political Science and Law.

There are also strong psychological consequences for administers of the injection. Judicial officers are reportedly under enormous pressure when they lethally inject convicts. Some have complained that they felt dizzy from the vapors from the contents of the injection, especially sodium cyanide.

Xu said all prefecture-level cities in China are equipped with the lethal injection system.

"Lethal injection protects criminals' dignity, even in their last moments," he said, adding that the means should be considered as the first option of execution even if it is not written into the law, Xu said.