New Delhi: Investigation in Pradyuman murder case has revealed illegality and destruction of evidence by Gurugram Police, Central Bureau of Investigation (CBI) sources said on Sunday.

Role of four Haryana police officials is being investigated in the murder case of the Class 2 schoolboy.

Earlier on Wednesday, the murder case of the seven-year-old Ryan International School student took a new turn after the CBI arrested a class 11 student of the same school and gave a clean chit to the bus conductor, who was arrested by the Gurugram Police for the murder and sexual assault of the child.

Bus conductor Ashok Kumar, who was arrested initially, has decided to file a case against police officers who 'framed' him.

"Now it is almost clear that my son Ashok was framed and made a scapegoat. We have decided to file a case against Gurugram Police SIT (special investigation team) officers who framed and used torture and even drugged him to confess before the media that he had committed the crime," said Ashok's father Amirchand.

Pradyuman Thakur, was found dead inside the toilet of school premises, with his throat slit on September 8.

Earlier, the CBI produced the accused, who is a minor, before the Juvenile Justice Board (JJB) and demanded his six-day custody.

The accused also confessed to his crime in front of his father, the CBI had told a juvenile court.

The CBI said that the accused committed the crime in order to postpone the parents-teachers meeting and the exams.

Meanwhile, the accused student has been sent to Faridabad observation home where he will be kept until the next hearing in the case on November 22.