It is suspected that a few kidney transplants, which were facilitated by the racketeers, were done by the doctor.
However, so far there is no evidence to prove his intent but the roles of his personal secretaries are under scanner, an official privy to the investigation said.
During investigation, it has also emerged that some of the recipients who procured kidney from the racket had used forged documents to hide their addresses. The police has short-listed the names of three senior doctors from the hospital's in-house assessment committee for verifying documents related to transplants, the official said.
The three of them are likely to be questioned first as they had cleared the papers in connection with the surgeries under police scanner. Meanwhile, two particular donors associated with the racket are likely to be arrested, the official said.
Also, the teams which were sent across cities to nab the racket's kingpin, Rajukumar Rao, who is believed to be associated with similar rackets in Nepal, Sri Lanka and Indonesia, are likely to return by tomorrow.
Suspecting the involvement of some senior staffers and even doctors in the racket, Delhi Police has served notices under CrPC sections 90 and 160 to the higher authorities of Apollo Hospital asking them to join probe and provide documents pertaining to kidney transplants carried out in the hospital in the past few months.
They will be scrutinised by a 25-member special team set up to crack the entire nexus, the senior official said. Two more prominent private hospitals in the city have come under the police scanner.
With the arrest of five persons, including the personal secretaries of a senior nephrologist in Apollo Hospital, police had unearthed the kidney trading racket.
The racket used to lure poor people across several states to sell their kidney off and also hound for people desperately looking out for kidney for transplant. They allegedly forged documents to establish relationship between the donors and the recipients in order to adhere to the law.
Police has so far come across five cases of kidney transplants conducted in the city through this racket and during interrogation the accused disclosed about 10-15 more transplants conducted at Jalandhar and Coimbatore in the past two years, an official said.
They used to charge Rs 40-50 lakh from the recipients, of which not even 10 per cent reached the donors. Earlier, Indraprastha Apollo Hospitals had said, "We are cooperating and providing to them all information required to help them in their investigation. This matter is of grave concern and our teams are extending all support to the police."