The SIT constituted by the Haryana Police to investigate the case had earlier arrested the school bus conductor Ashok Kumar along with murder weapon.
The initial eight seconds of the footage shows the now accused teenager calling Pradyuman to the washroom.
"There were many clues which a cop won't normally miss".
The CBI refused to formally offer any comment for the story.
The police, however, later, also detained two Ryan school officials along with the Principal for questioning.
According to the report, the class XI student's version of the development on the day Pradyuman's murder took place was completely different from what the CBI has been presenting before the media.
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The weapon can not be integrated into North Atlantic Treaty Organisation defences. The US-led coalition says it does not discuss the location of its forces.
He also looked up methods to remove fingerprints from the knife that he meant to use to commit murder, the sources added. The Gurugram police team had considered the boy a key witness, not the accused.
The report adds that legal experts say that a confession before a police officer does not hold any evidential value.
"We knew that he was innocent and pleaded for help but nobody heard us". Days later, the police arrested a school bus conductor for the murder; he allegedly confessed to killing Pradhyumn.
While the CBI has arrested a Class XI student, it is being suspected that a co-accused was involved and the victim's father too had claimed that he suspected involvement of some well-placed school official who was saved by making the conductor a scapegoat.
"The CBI officials/ investigating officer has openly flouted the orders of the board, whereby this board had specifically directed the CBI officials to conduct enquiry of the juvenile delinquent between 10 am to 6 pm during the course of enquiry for three days.The above observations of this board has been clearly been violated by the CBI", he pointed out.
Pradyuman Thakur, was found dead inside the toilet of school premises, with his throat slit on September 8. The CBI began probing the case from September 22 and arrested the Ryan student on November 8, It also gave a clean chit to the conductor.