This aerial photo taken on Dec 15, 2020 shows a view of Fuyang River in Cixian county, about 55 kilometers away from Feixiang district, Handan, north China's Hebei province. (PHOTO / XINHUA)

The killing of a middle school student allegedly by three other students in Handan, Hebei province, was a premeditated murder, local police's preliminary investigation show, China Central Television reported on Tuesday.

The victim, surnamed Wang, was a seventh-grader in Feixiang district of Handan. He was killed on March 10, and all suspects were taken into custody the next day, according to an official statement released on Sunday by the district's joint working group.

It is alleged that the accused, who went to the same school and are all under the age of 14, bullied the victim for a long time. Media reports said they are children of migrant workers

Some Chinese media outlets previously reported that the victim, 13, studied in a local middle school and went missing on March 10. His body was later found buried in a vegetable greenhouse in the district's Zhangzhuang village, about 100 meters from the house of one of three suspects.

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It is alleged that the accused, who went to the same school and are all under the age of 14, bullied the victim for a long time. Media reports said they are children of migrant workers.

Li Yafeng, an official from the district's public security bureau, told CCTV on Monday that after the killing, they immediately established a team of more than 60 police officers to start the investigation and carried out an autopsy.

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Now, the autopsy has been completed, and lots of evidence has been found, Li said, adding they will investigate every detail of the evidence carefully.

In response to some online posts saying the victim was buried in a two-meter deep pit and questioning whether there was parental involvement in the offense, Li said: "The burial pit for the body was 56 centimeters deep, and currently, no evidence has been discovered indicating the involvement of adults in the crime."

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In addition, "after preliminary investigation, this is a premeditated crime," CCTV quoted Li as adding. "In order to bury the body, the suspects dug in the abandoned greenhouse twice, on March 9 and 10, respectively."

The reports on the case has once again turned public attention on juvenile delinquents, as well as aroused discussions on the plight of left-behind children on Chinese social media.