CHANGSHA - A Chinese court on Tuesday acquitted a man who spent more than 11 years behind bars for the murder of a graduate school classmate.

Citing insufficient evidence, the Xiangtan Intermediate People's Court in Central China's Hunan province, overturned the guilty verdict against Zeng Aiyun, a former graduate student of engineering at Xiangtan University convicted in 2004 of murdering his classmate Zhou Yuheng.

Zeng had been sentenced to death three times by the same court. The Supreme People's Court rejected the verdicts and ordered a retrial.

Chen Huazhang, also the victim's classmate, was found to be the real killer. Chen poisoned Zhou with diazepam on Oct 27, 2003 as he was jealous of the attention Zhou enjoyed from their mentor. Chen deliberately laid a false trail and imputed the murder to Zeng, who was in love with the victim's ex-girlfriend.

Chen and Zeng were both arrested on Nov 11, 2003. Zeng was sentenced to death while Chen received life imprisonment.

Chen was sentenced again to life imprisonment on Tuesday and fined 178,143 yuan (29,108 US dollars) as compensation to the victim's family.