The woman's body was discovered only when the children's grandfather visited them on December 3, the report said.
When the police arrived, Wu appeared unperturbed by what had happened and initially claimed his mother had taken her own life, the report said. It was only later, when he was in custody, that he admitted to killing her as an act of revenge for the beating he had received. Chen's body was found to have more than 20 stab wounds.
After three days in police custody, Wu was released without charge. Under Chinese law, children under the age of 13 cannot be held criminally responsible.
The case sparked fresh debate over the handling of such cases, with many people in the local community airing their concerns.
"We're all saying that he got away without punishment, and we're afraid he will do something like it again when he gets back to school," a local resident was quoted as saying.
Wu's relatives want the boy to return to school but he has yet to be allowed to do so, the report said. He is currently staying at home with his father, who had been working in Zhuhai, Guangdong province, but returned to Sihushan after hearing what had happened.
"He's so young. How can we punish him?" one of the boy's relatives said. "What kind of man will he become if he doesn't go to school?"
Professor Pi Yijun, an expert in juvenile delinquency at China University of Political Science and Law in Beijing, said the process for dealing with serious offenders aged under 14 had long been a grey area.
Under Chinese law, children aged 14 to 16 who are convicted of serious crimes can be sent to juvenile delinquent prisons, while those aged 13 to 17 and charged with minor offences are sent to juvenile delinquent schools where they are confined during the week but allowed to return home at weekends.
"In my opinion, in this case, the other parents have good reason to be afraid," Pi said. "It's unsuitable to send someone as dangerous as he [Wu] is to school. We can't erase such an intentional wrongdoing for the sake of protecting a child's rights.
"The management of juveniles like Wu is a big mess," he said. "There should be a place specifically designed for them."
- South China Morning Post