The submission was made by the police in its status report filed before Chief Metropolitan Magistrate Gagandeep Singh in pursuance to the court's order for further investigation.
The police said it had recorded the statement of injured worker Roop Prakash who had said that Lalit Goyal, partner of main accused and factory owner Manoj Jain, and Jain's son Aditya were present in the premises on January 20 when the blast took place. They had locked the main gate from outside, it said.
The police also told the court that one of the supervisors of another firecracker factory, owned by the same persons, was needed to be interrogated in connection with this matter, but he has not joined the investigation despite repeated attempts.
The supervisor has not joined the investigation despite repeatedly calling him and now he has switched off his mobile and gone to his native village in Uttar Pradesh, the cops said in the status report.
The police said that it was also awaiting the postmortem reports of the 16 deceased persons and efforts were underway to get the details of one unidentified woman.
The court had on January 31 remanded the owners of a firecracker storage unit judicial custody. Jain was arrested on January 21 and Goyal on January 27 and sent to police custody.
The plea sought transfer of the probe from Delhi Police, alleging that "no fruitful investigation" had been made so far.
A fire had broken out in the storage unit on the ground floor of the two-storey building in Bawana on January 20 and ripped through the structure. Of the 17 killed, 10 were women. A man and woman were injured in the incident.
The court had earlier dismissed the anticipatory bail plea of Goyal saying the charges against him were "serious".
The police had alleged that both the accused were running the factory without licence and explosive materials were procured from outside Delhi. It had also claimed that the explosive materials were brought to the city without any permission or checking.
An FIR was registered under various provisions of the IPC relating to culpable homicide not amounting to murder and negligent conduct with respect to fire or combustible material. The maximum punishment for the offences is 10 years.
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