HONG KONG — The alleged murder of a 13-year-old boy by his classmates in rural northern China has shocked the nation, igniting heated debates about school bullying, juvenile crime and the plight of tens of millions of children raised in the absence of their migrant worker parents.

Three teenagers have been detained by police on suspicion of killing the boy at their junior high school in a village on the outskirts of Handan city in Hebei province, after his disfigured body was found buried in an abandoned greenhouse, state media reported last week.

Authorities in Handan said the boy, identified by his surname Wang, was killed on March 10, and that all suspects were taken into police custody the following day.

The crime had apparently been planned, as investigators had found the suspects started digging Wang’s shallow grave a day before he was killed, according to police.

Wang’s family and their lawyer said on social media the boy had long been bullied by the three classmates, who are all under age 14.

Their young ages, the accusations of bullying and the gruesome nature of the allegedly premeditated murder drew wide attention and outrage. Discussions about the incident have dominated Chinese social media in the days since, drawing hundreds of millions of views, with many calling for severe punishment of the perpetrators, including the death penalty.

The tragedy also put the spotlight on China’s generation of “left behind” children, living in rural areas often in the care of relatives, as their parents seek work in cities. Wang and the three suspects were all children of rural migrant workers, state media reported.

The welfare of “left behind” children has become a hidden sacrifice of China’s rapid economic rise, propelled by hundreds of millions of rural migrant workers who spent years toiling away from home to provide for their family.

More than one in five children in China – nearly 67 million under age 17 – are left behind by their parents, according to the country’s latest population census in 2020. Numerous studies and surveys have shown that such children are more vulnerable to mental health problems like depression and anxiety, and to abuse and bullying.

Wang’s death is the latest in a string of tragic incidents involving “left behind” children that have caused public uproar in China in recent years. These children were often victims, but in some cases also perpetrators, of violent crimes.

“I think this incident may be just the tip of the iceberg. The entire group of ‘left behind’ children needs more mental health support,” said Shuang Lu, an assistant professor in social work at the University of Central Florida, who has studied the well-being of these children.

Wang, who was living with his grandparents while his father worked in a coastal province, went missing on the afternoon of March 10 after leaving home to meet his classmates, the state-run Beijing News reported.

He was last seen on security camera footage taken from a store by the school gate, sitting at the back of a scooter around three of his classmates.

Before he vanished and his phone became unresponsive, all his money on WeChat, China’s super app, totaling 191 yuan ($26) was transferred to one of his classmates, according to his father, who rushed home upon learning he was missing and logged in to his son’s social media account in search of clues to his whereabouts.

The next morning at the school, police questioned the three classmates, who had previously denied to Wang’s family that they had seen the boy. One of them eventually told the police Wang had been killed and revealed where he was buried, according to the Beijing News.

The overgrown greenhouse surrounded by dry weeds was only about 100 meters (330 feet) from the home of one of the suspects, according to the Beijing News. The boy’s uncle, who identified the body, told the outlet that Wang’s face was “severely damaged.”

Wang’s father wrote on Douyin, the Chinese version of TikTok, that his son was “beaten to death” and his body disfigured “beyond recognition.”

“(I) hope the government will be fair, open and just, impose severe punishment, and that the murderers will pay with their lives!” he wrote underneath a video showing screenshots of the security camera footage that captured his son’s final appearance in public.

Wang’s father did not respond to CNN’s request for comment.

The family’s lawyer, Zang Fanqing, said in a video posted on social media site Weibo Monday that Wang had “suffered long-term bullying from three of his classmates.” The post has since been deleted.

Another classmate told state broadcaster CCTV the three suspects had repeatedly locked Wang in a shed when they went to the bathroom during class breaks.

“(Wang) once wrote a note to the classmate sitting in front of him, saying he didn’t want to go to class, he wanted to die,” she told the broadcaster.

Wang’s aunt told CCTV the boy had recently been reluctant to go to school and would often ask his grandfather for cash before he went.

“We thought the kid just wanted to buy some yummy food, so we didn’t think much of it. Now thinking back, it all feels a little strange,” she said.

She blamed herself for not noticing the signs, recalling a post Wang had written on social media saying he had suicidal thoughts.

“I thought he was under academic pressure, so I told him: ‘Don’t feel any pressure about your studies. It doesn’t matter whether you study well or not,’” the aunt said.

Concerns over bullying and violence among school children have been rising across China, as a growing number of incidents have been filmed on cellphones and spread on short-video platforms.

“Left behind” children are particularly vulnerable. In a study published in 2021, nearly one in three of them reported recurrent bullying and victimization, compared with one in four rural children who live with their parents.

A 2019 survey on “left behind” kids by a Beijing-based NGO found 90% of them suffered emotional abuse, 65% experienced physical violence and 30% said they had been sexually abused.

Juvenile crime has also risen in China in recent years. Between 2020 and 2023, prosecutors charged 243,000 minors, with an average increase of 5% per year, CCTV reported earlier this month.

In 2021, China lowered the age of criminal responsibility from 14 to 12 in an amendment to its criminal law, though it mandated that such prosecution must be approved by the Supreme People’s Procuratorate, the country’s top body for investigation and prosecution.

Lu, the US-based academic, said the law is only one aspect of dealing with the problem after it has occurred, but the key to prevention lies in better care for children’s mental health.

“There must be some deep-seated family or social reasons behind a child’s behavior. If their mental health problems are not fundamentally addressed, (this kind of tragedy) could happen again in the future,” she said, citing the need to improve mental health awareness, prevention and intervention among children in China’s vast countryside, where the topic is still often stigmatized.

In the long run, the plight of millions of “left behind” children can only be addressed by narrowing the yawning inequality between the countryside and cities, Lu said. For decades, China’s booming cities and factories have relied on the cheap labor of countless migrants without granting them access to urban social welfare benefits, including education for their children.

Many “left behind” children only get to see their parents during holidays, not more than a few times a year.

On Douyin, Wang’s father posted a video of his son playing by the sea and looking back at the camera with a smile.

“Dad took you to see the ocean for the first time and asked you if you liked it? You said you did, and since then every summer break I would bring you here. Even now, I feel like I’m in a dream,” he wrote.

“Dad will never take you to see the ocean again, my poor child.” — CNN