Yang is the latest wrongfully convicted person to have his name cleared, as the leadership pushes for courts around the country to redress unjust cases as part of its move to strengthen the rule of law and avoid potential sources of social unrest.

Yang was accused in 1995 of murdering his girlfriend but insisted he was innocent when the case went to trial. The court said he strangled her, and gave him a suspended death sentence, which on the mainland is usually converted to life in jail. But Yang maintained his innocence, and his family petitioned repeatedly for provincial authorities to review the case.

The judges bowed and apologised to Yang and his family members who were in attendance. They also called on the police to restart the investigation for the killer, Zhang said, adding the family had not decided yet whether to seek compensation.

The Guizhou prosecutors' office started to review the case last October, although it was not clear what prompted their decision.

When the retrial began in June, the prosecutors agreed the original ruling was flawed.

A key witness at the trial in 1995 said she had only heard that Yang was at the murder scene. She was in police custody on suspicion of murder at the time, and the charge against her was dropped after her testimony.

"The ruling was based on unclear facts and insufficient evidence. The legitimacy and objectivity of key testimony were uncertain. There is contradicting evidence," Zhang quoted prosecutors as saying telling the court.

Yang is the latest person to have his name cleared by the courts. Last December, the Inner Mongolia Higher People's Court said Huugjilt, who was 18 when he was executed in 1996, was innocent. He had been wrongfully convicted of rape and murder.

Nian Bin in Fujian was declared innocent of poisoning his neighbor's children last August, and set free after eight years in jail.