Delhi Police, which searched Chief Minister Arvind Kejriwal's residence on Friday for CCTV footages in connection with the alleged assault on Chief Secretary Anshu Prakash, said no cameras were installed in the room where the incident reportedly took place.A senior police officer said they would go about the investigation based on the coverage by cameras installed in the corridor and added that seven of the 21 CCTV cameras in the house were not functioning."Going by the coverage by CCTV cameras outside the drawing room and in the corridor, we will try to understand the movement of people before and after the incident," Additional Deputy Commissioner of Police (DCP) Harendra Kumar Singh said."The time of cameras at the Chief Minister's residence was running behind by 40.43 minutes," he said, adding that hard disks of the cameras had been seized.A forensic team was also present during the search, so that evidence could be collected in a certified and professional way, the DCP added.These teams would also look into why seven cameras were not functional.So far, interrogation of the Chief Minister has not been done.The police official declined to comment on whether the Chief Minister and his deputy Manish Sisodia would be interrogated.The police also interrogated the people responsible for maintenance of the CCTV cameras in the Chief Minister's residence.On Tuesday, the Chief Secretary had alleged that he was beaten up by two AAP MLAs Amanatullah Khan and Prakash Jarwal, in the presence of Kejriwal, on Monday night at the Chief Minister's residence where he had been called for an emergency meeting.The incident took place between 12.00 and 12.15 a.m, according to the police.The officer said that the CCTV footage was sought by them on February 20, but since there was no response, they had to conduct the search.