Long road to justice

Before retirement, Zhang Biao was a prosecutor in the city of Shihezi in the Xinjiang Uygur autonomous region.

In June 2008, Zhang and his colleagues at the people's procuratorate in Shihezi held a special session to study the materials. They decided that there were grounds for Zhang Gaoping's claims of innocence and that he might have been tortured to extract a confession.

"Zhang Gaoping was in low spirits, but a little bit arrogant when I first talked with him. He didn't trust judicial workers, but thought the law could give him back his innocence," he says.

But the right to review and re-investigate the cross-regional case belonged to the prosecuting authority in Zhejiang, where the crime had taken place, instead of Xinjiang, where Zhang Gaoping was imprisoned.

Zhang Biao sent more than 10 sets of materials, including photos and documents, to the procuratorate in Zhejiang and even China's top court. Each of these sets comprised at least 100 pages. But each time he was told the evidence was insufficient to overturn the convictions.

Zhang Lu, his daughter, says the prosecutor was very down during this period, and she often heard him sighing in despair when he returned home.

But Zhang Biao's despair came to an end after he received a letter from Zhang Gaoping in August 2008, saying he had learned an inmate Yuan Lianfang had reported a man had made a confession in Henan province in 2002.

"I was shocked Zhang Gaoping's nephew had confessed to the murder of the girl to Yuan while they were detention together," he says. "I immediately contacted the prosecutors in Zhejiang and Henan, aiming to make clear why Yuan had provided similar testimony in different cases."

In July 2010, Zhang Biao confirmed the Yuan in the two provinces was the same man, and he had forced other detainees to plead guilty by beating them in detention houses so as to get his own sentence reduced.