Just days after the autopsy report of an inmate at a detention house in Danfeng county, Shaanxi province, showed that he died of "severe injuries", a top forensic expert on Wednesday challenged the findings, saying the death was "natural".

Xu Gengrong, 19, "suffered from liver and lung diseases, which caused his death", Bai Ningbo, the chief forensic doctor of procuratorate of Shaanxi, was quoted as saying in the Time Weekly yesterday.

The latest report comes even as authorities probe the role of two police officials in Xu's death on March 8, just a week after he was detained on suspicion of stoning a schoolmate to death.