Police in southwest China have reopened an investigation into the death of a teenage girl, which has sparked violence protests involving up to 30,000 people on Saturday.

Police authorities in Guizhou Province published details on the death of Li Shufen, a 17-year-old student in Weng'an County, at a press conference in the provincial capital Guiyang on Tuesday night.

Wang Xingzheng, the provincial public security department spokesman, said Li was with her boyfriend Chen Guangquan and two other people before she jumped into the river and drowned on the night of June 21. The three tried to rescue her, but failed. Her body was recovered at 3 AM on June 22.

Wang gave no motive for the alleged suicide, but police sources who spoke to witnesses told Xinhua that Li wanted to die because her family had treated her badly.

The official account of her death was dismissed by her family and others who believe she was raped and killed by people who had connections with local government and police officials.

Forensic investigator Wang Daixing, who attended the conference, said there was no evidence that Li had sexual intercourse before her death and no indications of rape.

A third autopsy would be performed on Tuesday night by forensic experts sent by the provincial government, and the results would be published soon, said Wang.

Deputy director of Weng'an police bureau Zhou Guoxiang insisted that the three people who last spoke to Li -- Wang Jiao, Liu Yanchao, Chen Guangquan -- were from local villages and none had connections to any officials.

Over the past week since Li died, doubts have mounted and eventually led to a mass protest. Confrontations between police and the girl's relatives added fuel to the public anger.

Some of the protesters were students of a school where the girl's uncle Li Xiuzhong worked. Li, who is now in a local hospital, was confronted by a policeman named Zhang Min at the county's public security bureau and was badly beaten by unidentified men in the street after leaving the police station.

"We never expected such a major conflict. That was neither what we wanted nor what we could control," said Li, from his hospital bed, on Tuesday.

"My niece died in such an unintelligible way, and we simply demand a thorough investigation and a convincing result," he said.

Police have started to investigate into the beating, said Zhou Guoxiang, deputy head of the county police force.

Zhou denied claims that the girl's paternal grandfather and grandmother were also beaten, and insisted the couple were only contacted by the police once to assist investigation. "They are staying at home and fine," Zhou said.

The dead girl's paternal grandmother, Lu Xiuzhen, who was earlier interviewed by Xinhua, said the girl's father had departed for the provincial capital, Guiyang, to petition the government and could not be reached. The mother had "gone mad" since the incident, she said.

"There must be an explanation. There was no way she could jump into the river and kill herself. We can't accept that," she said.

On Saturday, the girl's family, followed by about 300 protesters, started to parade with placards reading "Return justice to the people" and "Petition for the people" at 4 PM. They were quickly joined by thousands of others on the street. The angry crowd assaulted and torched the buildings of the public security bureau and the county government.

More than 150 police and protesters were injured, but no deaths were reported. About 160 government offices and 42 vehicles were burnt. Fifty people, some of whom were local criminals, were taken into police custody, the provincial public security spokesman Wang said.

(Xinhua News Agency July 2, 2008)