Legal progress made over the past two years has helped prevent torture during criminal investigation and minimize miscarriage of justice, legal experts said.

Dai Peng, director of the criminal investigation department under People's Public Security University of China, said some police officers used to resort to torture to force suspects to confess, blaming the old criminal procedure law.

Police used to interrogate suspects at the police station rather than a detention center, and oral confessions were taken as evidence when they were charged.

Also, lawyers faced difficulties when trying to meet their clients during investigation, and couldn't defend them in a timely fashion.

Due to an amendment to the Criminal Procedure Law in 2012, the situation has changed, said Li Fang, a lawyer in the criminal defense committee of the All-China Lawyers Association.

Under the amendment, a suspect is put into a detention center for investigation following a physical examination, and the process is video recorded and kept for 30 days.

The amendment also stipulates that during investigation, the police have to be separated from the suspects to avoid physical contact, and the lawyers can meet their clients and review the case files without approval from public security departments.

"If the lawyers find any signs of torture, they report to the prosecutors at the detention houses or the superior public security authority," Li said.

Cancellation of the evaluation system based on the solving rate of criminal cases has also proved effective.

"Under the crime-solving rate system, police officers tend to emphasize results over process and some of them might use improper means to meet 'satisfactory' results," said Liu Liwei, director of Zhejiang Provincial Public Security Department.

He also said that those responsible for the miscarriage of justice will be punished according to the law, whether they are still on duty or have retired.

Zhang Yan and Yan Yiqi