Two Chinese men face the death penalty and a former executive faces life in prison, for their roles in the tainted milk scandal that led to the deaths of six babies, and sickened hundreds of thousands.

Investigators found that melamine was added to raw milk to make it appear to be higher in protein than it actually was.

Cattle farmer Zhang Yujun, 40, and Geng Jinping, a milk trader, have been sentenced to death.

Yujun was accused of operating an illegal melamine workshop in Shandong province in the east -- which produced an estimated 600 tonnes.

Jinping was found guilty of producing and selling toxic dairy products.

In addition to the death sentences announced on Thursday, the former head of the Sanlu dairy, where the scandal took place, was sentenced to life in prison by the Intermediate People's Court in Shijiazhuang.

In December, Tian Wenhuam pleaded guilty to producing and selling milk she knew was tainted.

In addition to the life sentence, the 66-year-old former highest ranking executive within the company was fined the equivalent of US$2.9 million.

She pleaded guilty in December to the charges.

But Tian got off lightly, family members of the victims charge.

"My granddaughter died. She (Tian) should die too, she should be shot. She has brought such harm to the public, to children," Zheng Shuzhen, of Henan province, who said her 1-year-old granddaughter died in June after drinking Sanlu milk," told The Associated Press.

According to reports, Sanlu itself was fined $7.3 million -- though the company has now been declared bankrupt.

The scandal broke in September 2008. It was eventually revealed that the company had known the milk powder was tainted, but still went ahead and allowed roughly 900 tonnes of product to go out the plant doors.

Production was eventually halted, but only after Sanlu's New Zealand partners intervened.

The stoppage by the world's largest producer of milk powder was followed by international product recalls.

The scandal came on the heels of other scares related to the health and safety standards of other Chinese-made products -- including a milk powder scare four years ago that left 13 babies dead.

Among the 12 sentences announced Thursday, two other life terms were handed down, while others were given jail terms of five to 15 years.