In 1995, Nie Shubin was executed after being convicted of a crime his family says he did not commit. Now, changes to the legal system could signal the end of a two-decade-long battle for a posthumous pardon, report Luo Wangshu in Shijiazhuang, and Cao Yin in Beijing.

After spending 20 years fighting to clear her dead son's name, Zhang Huanzhi is hopeful that a court will soon quash his conviction and grant a posthumous pardon.

Nie Shubin was executed in 1995 at age 21, having been convicted of raping and murdering a 38-year-old woman in Shijiazhuang, capital of Hebei province, the previous year. The woman cannot be named for legal reasons.

Ten years later, a man called Wang Shujin was arrested on unrelated charges of rape and murder, and while in detention, the then-38-year-old confessed that he had committed the crimes that cost Nie his life. Wang was later convicted of the crimes that had prompted his arrest. He was sentenced to death, but legal arguments related to his "confession" have delayed his execution.

Zhu Aimin, Wang's lawyer, said that when he last saw his client in May, Wang was in good physical condition and was sanguine about the future. "Wang told me that he was guilty of his crimes (including those for which Nie was executed) and was willing to take responsibility for his actions," he said.

Some Internet commentators have accused Wang of cynically confessing to the woman's murder to muddy the waters and prolong the legal arguments. In response, Zhu said Wang is poorly educated and has no Internet access at the detention house, "so the online comments that his confession is aimed at delaying his execution are wrong, I think".

Since Wang's confession, Zhang has constantly petitioned the courts to exonerate Nie. "I have nothing left in my life. My only desire is to prove my son's innocence," the 72-year-old said.

That may happen on Dec 15, when a decision will be made on whether the case will be retried. A ruling should have been made on Sept 16, but the Shandong High People's Court announced that the complexity of the case meant the decision would be delayed for three months.

It was the second time the ruling had been postponed, but Li Shuting, Zhang's lawyer, said a number of factors, including government-sponsored judicial reforms and the high level of legal and media attention, mean "the case won't go cold" this time.

Cheng Lei, an associate professor of law at Renmin University of China, has recently conducted research at the court in Shandong. "The judges mentioned this high-profile case without any prompting. They told me they have been ordered to review every piece of evidence. They assured me that they cannot and will not miss any detail, no matter how small," he said. "The probability that the case will be retried is, I think, high."

A mother's instinct

Sitting in her dining room, Zhang looks like thousands of other farmers across China, but the moment she starts talking about the case, legal jargon flows from her lips, setting her apart from her rural peers. Since 1995, she has visited the court every month in her quest for answers.

"From the very beginning, I refused to believe the case was true. My son, the boy I gave birth to and raised, was not capable of doing that. But back then, I didn't know what was wrong, and I didn't know how to prove his innocence. I knew nothing about the law. Maybe it was just a mother's instinct," she said.

Zhang had no idea how to lodge an appeal or initiate a case review, so her submissions were rejected repeatedly.

The turning point came in 2005, when Zhang was told that Wang had confessed. She was convinced that her "mother's instinct" had been correct.

The development attracted widespread public attention, which resulted in offers of assistance from lawyers and media experts.

With their help, Zhang began an "instructive" petition which, she hoped would result in a review that would clear Nie's name. "Because the real killer had been caught and had confessed, I thought my son would be declared innocent with very little delay," she said.

In the end, the Hebei High People's Court refused her request to review the case, and a stalemate reigned until 2007, when the Supreme People's Court ordered Hebei to reopen the investigation.

"It was one of the very few happy moments in my life in the past 20 years," Zhang said.

She was informed of the decision by an employee of the Supreme Court during one of her regular trips to petition officials in Beijing. "He told me that the Supreme Court had ordered the court in Hebei to review the case. I was also told that letters confirming the decision, addressed to the court and myself, had been sent out," Zhang said. "I will never forget the scene - I can even remember the numbers on the official's uniform."

Zhang heard nothing until 2014, and had begun to doubt if she would ever see justice done. She was confused and despondent: "I thought 'What if I don't live long enough to see a result?' and 'if I die, no one else will make as much effort as I do.'"

Although she was concerned about her own health, Zhang was also worried about the burden being shouldered by her daughter, Nie's older sister. "I was very downcast and cried for two days. I wanted to make everything right, for the simple reason that I wanted people to know the truth about my son. I never considered giving up - that's not my way," she said.

In December last year, the Supreme People's Court ordered the court in Hebei to hand the case over to the Shandong Provincial High People's Court for review. It was the first time that China's top judicial body had ordered a court to review the findings of one of its peers.

Zhang was thrilled. "I received a lot of phone calls from relatives, friends, lawyers and journalists that night, from about 7 pm to 11 pm. I was unable to fall asleep," she said.

In March, the court in Shandong assigned lawyers to read the documents related to the case. "Zhang burst into laughter outside the Shandong court. It was the first time I had heard her laugh for years," said Li, the family's lawyer since 2005.

In April, the court organized a forum to hear opinions from judicial officers and lawyers on both sides, and announced it would publish the results of the forum on June 15. However, the complexity of the case led to publication being postponed, first to Sept 15 and then Dec 15.

To make the deliberations more transparent, the court has used its micro blog to disclose ongoing procedures, updates and unsolved quest-ions thrown up by the case.

Although the lengthy process has sparked discussion, Renmin University's Cheng said that under Chinese law, there are no restrictions on the time that can be spent preparing for a hearing of this nature, and the court in Shandong is acting in accordance with legal procedure.

"The case has lasted a long time, which has been a challenge for the judges sifting the evidence. Verifying the evidence will also take time," he said. The decision to refer the case to the court in Shandong, rather than Hebei, where the original trial and sentencing took place "also presents difficulties because the judges in Shandong had to familiarize themselves with every aspect of the case, so it has taken a long time," he said.

Zhu, Wang Shujin's lawyer, said the case is so high-profile that the court is right to take time deliberating a retrial. "The decision to retry or not, and the attitude of the court could become 'touchstones' as to whether the country has rule of law," he said. "Because of this, I don't mind waiting a little longer. After all, delivering a fair verdict is the most important thing. I can't control the time the Shandong court spends reviewing and investigating the case, but as lawyer, I believe in justice and I'm looking forward to hearing the arguments," he added.

Li is confident that the chances of a quashed verdict and posthumous pardon are high, despite the delays.

"Based on the documents I reviewed and the research I have conducted for 10 years, it's highly likely that Nie was wrongly convicted," he said.