Khirwar, while addressing the media in Gurugram, said when the case of Pradyuman Thakur murder was handed over to them, police was still trying to collect the evidence.
"We had carried out investigation at a very early stage and then we handed it over to the CBI, which I am hopeful, will bring culprits to book and bring justice to the family," Khirwar said.
"We had not concluded investigation. We had not done a specific role attribution. Evidence was in process of being gathered," he added.
The police commissioner said that they were not under pressure to save the culprit and asserted that they did "honest attempt to bring justice to the family".
Earlier on Wednesday, a Gurugram court sent Class 11 student of Ryan International School to three-day CBI remand.
The student was produced before the Juvenile Justice Board, after the CBI sought six-day custody of the student.
Meanwhile, the victim's family has demanded that the juvenile student be tried as an adult and accordingly be given a harsh punishment.
The CBI has given a clean chit to the arrested bus conductor in connection with the case
Pradyuman was found inside the toilet of the school with his throat slit on September 8.
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