The man in the photograph, Qian Yunhui, 53, has become the latest Internet sensation in China, as thousands of people viewing the image online since the weekend have accused government officials of gruesomely killing Mr. Qian to silence his six-year campaign to protect fellow villagers in a land dispute. Illegal land seizures by officials are common in China, but the horrific photographs of Mr. Qian’s death on Saturday have ignited widespread fury, forcing local officials to offer explanations in a news conference.

It is the latest in a string of cases in which anger against the government has been fanned by the lightning-fast spread of information online.