Three accused – including a bus conductor – from Gurugram’s Ryan International School were sent to one-day custody of the Central Bureau of Investigation on Saturday in connection with the death of a seven-year-old student on campus, ANI reported. The three were arrested by the Gurugram Police within a week after the murder on September 8.

Earlier in the day, teams from the CBI and the Central Forensic Science Laboratory made visits to the school as they began the inquiry into the Class 2 student’s death, the Hindustan Times reported.

The forensic team collected evidence from the toilet in the school premises where the student was found with his throat slit. The CBI team questioned teachers and other staff about the sequence of events before and after the boy’s body was found.

On Friday, the CBI registered a case hours after the father of the deceased student said he would approach the Supreme Court if the case was not handed over to the agency soon. The Gurugram Police also summoned the owners of Ryan International School to be questioned on September 26.

Haryana Chief Minister Manohar Lal Khattar had, on September 15, announced that the state government had handed the case over to CBI. “It has been more than a week, and the case has still not been transferred to the CBI,” the boy’s father told the Hindustan Times on Friday. “Crucial evidence will be lost and tampered with if the CBI does not inspect the spot soon.”

The seven-year-old was found dead with his throat slit in the school toilet on September 8. An autopsy had revealed that injuries on the boy’s neck, inflicted by a sharp-edged weapon, were the cause of his death. The student’s trachea and food pipe were damaged in the attack, the report said.