A Chinese man arrested after a riot in Guangdong province in September has died in police custody.
In an online announcement, the municipal government of Shanwei said that the suspect, Xue Jinbo, "suddenly felt unwell" on Sunday.
The authorities said he was rushed to hospital but died from cardiac failure.
Analysts say his death threatens to stir tension again in the area, where villagers accuse corrupt officials of stealing land for development.
The Shanwei government statement said forensic experts had been invited to conduct independent investigations.
Mr Xue was arrested last week in Lufeng, a city under Shanwei's jurisdiction.
The initial riot broke out on 21 September in the village of Wukan, where government buildings including a police station were attacked.
Villagers claim that corrupt officials and powerful developers have illegally acquired hundreds of hectares of land in recent years.
Laws are in place to protect farmers, but are often ignored at local level.
Local authorities have since promised to investigate the issue, but reports suggest that villagers have continued to protest.
There are tens of thousands of riots in China every year. They are described as "mass incidents" by the authorities.
Some of the highest-profile recent protests have been in Guangdong province, a manufacturing hub where factories turn out about a third of China's exports.