A former Beijing district police head sentenced to 20 years in prison for bribery says he was tortured by police to confess, Beijing Times reported on Monday.

Chen Baode, former director of Beijing Daxing district public security bureau, instructed his lawyer to file a complaint on Sunday to Liaoyuan City People's Intermediate Court in Jilin province.

Chen said that when he was detained by police in March 2012 he was tortured. During the interrogation, his hands were bound to a chair with a chain. He said police also pressed his knees on the ground and kicked him, resulting in injuries to his forehead and knees.

After his complaint was filed on Sunday, the local judicial authority began an investigation into the case, the newspaper said.

According to the court verdict on Jan 10, Chen and his son accepted bribes of up to 15.28 million yuan ($2.47 million) to help an acquaintance win construction contracts. He was also charged with embezzling 354,900 yuan of public funds.

Chen was sentenced to 20 years in prison by the court on charges of corruption and bribery. He said he did not appeal to a higher court immediately because his son’s trial was ongoing.

But after his son received a sentence with a reprieve, Chen said it was time to appeal for a retrial of his case.