SHANWEI, Guangdong - The death of a man in detention was due to sudden cardiac death, sources with the Shanwei No 2 People's Hospital said.

The death of 42-year-old Xue Jinbo, who had been involved in a land dispute in Guangdong province, was not due to external force, according to an initial check of the body on Wednesday.

Liu Shuiping, a chief legal medical expert of Sun Yat-sen University Forensic Authentication Center, said bruises found on Xue's knee and wrists were not enough to determine that the suspect had been beaten before his death.

"The bruises might be related to handcuffs and the grabbing by prison officials while sending Xue to the hospital, and a large number of purplish spots found on the backside of the body are just normal discoloration from blood gathering after death," Liu said.

"We did not find obvious scars and fractures on his body," he added, showing dozens of pictures taken during the medical check.

Xue, who was involved in a land dispute in early September in Lufeng county, Shanwei city, died in a local hospital on Sunday, two days after he was detained.

A complete medical check is yet to come, said Zhang Zhanzhong, chief prosecutor of Shanwei procuratorate.

"Xue's family has so far not agreed with a complete postmortem investigation," he said.

A work group has been set up by local prosecutors and police officers to conduct a thorough investigation into Xue's death, Zhang said.

Sources with the local government said that Xue had a history of asthma before he was detained.

"He had taken medicines in the detention house. His family had sent him some medicines, which are used to cure asthma, heart disease and stomach illness," said Zhang.

Rumors spread online after Xue's death that the suspect was beaten to death and other suspects had been also interrogated by beating.

On Sept 21, hundreds of protesters blocked a major local highway over a land dispute, while the others went to petition outside of the government building in Lufeng county.

Six police cars were damaged and more than 10 policemen injured in the dispute, the local government sources said.

Five villagers, including Xue, were later held in custody for violating the law and destroying public facilities.

A number of officials in Lufeng county were also detained for neglecting their duties and violating the law in the land dispute, said Wu Zili, acting mayor of Shanwei.

"We have also frozen the land project involved in the dispute. We have given, and will always give, priority to protect villagers' reasonable rights and property," said Wu, who has been acting mayor since early September, when the previous mayor was promoted.

The dispute in question started when a local livestock company and the Country Garden Co, one of China's major property developers, proposed new buildings on a piece of land they bought from the local government, but which the farmers said they owned.

Some villagers again organized five roadblocks on Saturday - before Xue's death - to prevent government and police officials from conducting investigations in the village.

"Life in the county has been greatly disrupted by the blockades," said Wu, adding local villagers have voluntarily removed three roadblocks to maintain a smooth flow of traffic.