The killing of a 13-year-old boy in northern China last week, for which three boys are in police custody, has triggered a heated discussion in the media on juvenile crime and the plight of children left at home by migrant workers.

Police arrested three boys and took them into custody after they allegedly bullied and killed the junior high school student in the small city of Handan, in Hebei province, on 10 March, and then buried him in a shallow pit, state media reported. So far, no charges have been laid.

Local police are investigating the case as a homicide and have set up a team of more than 60 people, state media broadcaster CCTV News reported. Police in Handan’s Feixiang District declined to comment, and district propaganda officials referred Reuters to CCTV reports on the case.

State media said the victim and the three boys were children of rural migrant workers who spend most of the year working in large cities, leaving childcare duties to grandparents and other relatives.

Relatives of the victim and their attorney said in interviews with Chinese media and in posts on social media that the boy had long been a victim of bullying.

There are nearly 67 million so-called “left behind” children, 2020 census data shows, and academic studies show that these children are at higher risk of mental health issues, becoming victims of bullying and criminal behaviour.

In the last recorded moments before the 13-year-old boy’s death, authorities said surveillance footage showed him sitting on a scooter, surrounded by the three boys. An hour later, his phone went dead, triggering a frantic search by relatives.

The following day, police in a village discovered the boy’s body buried underneath a tarpaulin in an abandoned greenhouse.

The case has gripped the nation, with many Chinese expressing their outrage on social media.

“Public Trial! National live broadcast,” wrote a user on the Chinese social media platform Weibo. Other users called for the perpetrators to be punished, while some said that bullies across the country were watching the outcome.

In 2021, China lowered the age of criminal responsibility from 14 to 12 for certain crimes. The Global Times, citing experts, said the case could be the first that goes to court under the new legislation.

David Zhang, a Beijing-based defence lawyer, told Reuters the crimes the law covered include intentional homicide, intentional injury causing death and injuring someone by cruel means resulting in disability.

With Associated Press and Reuters