In the last recorded moments before the 13-year-old boy's death, he was filmed by surveillance cameras sitting on a scooter, surrounded by three of his classmates. An hour later, his phone went dead, kicking off a frantic search by relatives.

The following day, officers in a village in central China made a sickening discovery: the boy's body, buried in an abandoned vegetable greenhouse underneath a tarp.

Now, his three teenage classmates have been detained on suspicion of murdering the boy in a case that has riveted China, setting off outrage and frenzied debate over the young age of the suspects and soul searching about bullying and social responsibility in the Chinese countryside.

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Police in Feixiang district of Handan city identified the boy only by his last name, Wang. In a short statement Sunday they said the boy was killed on March 10 and that the suspects were detained the following day.

Wang’s relatives and their attorney said in interviews with local outlets and in posts on social media that the boy had long been a victim of bullying, and was forced to give money to one of his classmates before he was killed. They said police identified the suspected killers after reviewing the surveillance footage and questioning his classmates.

"He was beaten alive and his body was disfigured beyond recognition," Wang’s father wrote on Douyin, a Chinese social media platform. "I hope the government will be fair, open and just, punish them severely, and that the killers will pay with their lives!"

Wang's father, aunt, and grandmother did not immediately respond to requests for comment. A person answering a phone number listed for the attorney's law firm told The AP to wait for comment, saying they were swamped with interview requests.

Wang and the suspects are all under the age of 14. Local media reported they were "left-behind" children, a common phrase in China used to describe kids in the countryside often left with grandparents because their parents work in faraway cities.

As details of the tragedy emerged this week, it renewed concern over the social and psychological welfare of such children, their exposure to violent content online and the ability of the country's social services to care for them.

"The attention paid to the mental health of minors in the countryside is too little," said one commentor on Weibo, a Chinese social media platform. "I think this sort of thing could happen again."

The perpetrators’ unusually young ages drew widespread attention in China, with posts and videos from Wang's relatives garnering millions of views and thousands of comments. Zhang Dongshuo, a defense attorney in Beijing unaffiliated with the case, says that Wang's death is the latest in a series of juvenile murder cases in China that have sparked debate on how old a child should be before being held responsible for a crime.

"Generally speaking, these kinds of cases involving minors are rare," Zhang said. "But recently more and more of these cases have been reported by the media, and it's been triggering discussion in Chinese society over revising the age of criminal responsibility."

In 2019, a 13-year-old boy who confessed to sexually assaulting and murdering a 10-year-old girl in a northeastern coastal city avoided criminal charges because Chinese law at the time stipulated that only those over the age of 14 could be held criminally liable. Two years later, the government lowered the age of criminal responsibility to 12, but mandated that prosecution only take place if approved by the Supreme People’s Procuratorate, China's highest prosecuting authority.

Zhang added that the lack of parental guidance for "left behind" children has been a longstanding social issue, but that the question of how they should be raised has not been fully resolved.

"Many people think schools and the government should take responsibility for children's education, but that means if the relevant government departments and schools don't educate them effectively, then it's highly likely this minor is left in an educational vacuum," he said.

State media have given Wang's death widespread coverage, though there are signs that Chinese authorities are keeping a close eye on public sentiment given its sensitivity. On Sunday, the family's attorney, Zang Fanqing, was abruptly cut off on a live broadcast after saying he and Wang's father were barred from seeing the boy’s body. The next day, Zang said on social media that they were allowed to see the body.

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A number for the Hebei publicity department rang unanswered, and a faxed request for comment did not go through because the line was busy. A number for the principal of the school the boy attended rang unanswered, as did numbers for relatives of two of the suspects.

A public statement from local police Sunday asked the public not to "spread rumors" to protect the victim’s privacy and "avoid further harm" to the boy’s family.

"Relevant departments have made every effort to comfort the victim’s family and deal with the aftermath, and all aspects of work are being carried out in an orderly manner," the statement said.

After seeing Wang's body, his family has signaled they intend to pursue criminal charges. In a video Wang's father posted Monday, he said the sight of his son was "crueler than I imagined."

"Your father isn't scared, he is only upset and furious," Wang's father wrote, addressing his son. "Wait for your father to avenge you!"