Five days after the first dead pig surfaced in a river that flows through Shanghai, officials have yet to give answers of where exactly they come from.

The slow response and lack of information has prompted a wave of condemnation on Chinese social websites, adding to the public’s wide distrust of authorities.

A popular columnist and military expert, Zhao Chu, expressed strong doubts over an official statement that most of the pigs had frozen to death.

“When you said more than 10,000 pigs froze to death, in my opinion, you are lying. [You] must be covering something up,” he posted on Sina Weibo.

On Monday an official from Zhejiang's provincial agricultural department said most of the pigs had died due to cold weather, not illness. But average winter temperatures in Jiaxing, where the hogs are said to have orginated, never dip below zero degrees Celsius.

More than 3,300 dead pigs were pulled out of a section of Huangpu River, a source of drinking water for Shanghai. Porcine circovirus, a common hog disease, was found in a sample taken from the water, the city's animal disease control department said.  

Another Weibo user jokingly speculated that the pigs had sacrified themselves to make a stand on social issues, including:

1. Refusing to be over-fed with antibiotics.

2. Refusing to inhale the polluted air.

3. Starving to death from no supply of Hong Kong milk powder.

4. Drowning in an attempt to drink water from Huangpu River after refusing polluted water from their owners.

Another blogger, who goes by the handle Zuoyeben, or homework booklet, wrote: “People’s quality [of life] is on the rise. At least they did not make the dead pigs into sausages and ham.”