The Delhi Police on Saturday detained a fourth student accused in the case of a Class 9 boy’s death in the toilet of a school in Karawal Nagar, PTI reported. The boy was found unconscious inside the toilet on Thursday and died later in hospital.

CCTV camera footage of the school showed five students, including the boy, fighting inside the toilet. On Friday, the police detained three of them, but the fourth was absconding.

Deputy Commissioner of Police (Northeast) AK Singla earlier told the Hindustan Times that the CCTV camera footage led them to the four students. “We questioned the students and found that they had punched the boy after an argument,” Singla said.

The students allegedly punched the boy in the neck and face, and the police said he could have died of internal injuries, NDTV reported. An officer told the Hindustan Times that an argument over a wristband got the student killed.

Soon after the incident, the school authorities claimed that the boy was suffering from diarrhoea, which caused his death. However, his family said he was beaten up by other students.

The police are looking into whether the school was negligent.