Police have also spoken to victim Mahendra Aggarwal's family to get clues.
A gym owner was shot dead in his office by three men in East Delhi's Preet Vihar on Friday, and took the CCTV recorder with them, making the probe more complicated, police said.
The victim, 45-year-old Mahendra Aggarwal, ran a chain of Energy Gym and Spa, and sold gym equipment too. He was in his company headquarters office above one of his gyms around 8 pm when three armed men entered and immediately fired a number of shots at him. A bullet to his head killed him, police said.
While escaping, the killers took away the recording device attached to the CCTV security cameras of the office.
Police are now scanning footage from other CCTV cameras in the area to get clues. A forensics team also inspected the scene of crime.
Police said relatives are being asked if they suspect anyone's involvement or any enmity he had.