The names of the three doctors emerged during the interrogation of the racket's kingpin Rajkumar Rao, who was allegedly operating in several states and is believed to have links with similar cartels in other countries, a senior police official said.
One of the three senior doctors is currently in the US. He was to return on Thursday but did not.
During investigation, police found blank papers signed by the doctor, which were allegedly used by his assistants to complete the formalities to facilitate kidney transplant surgeries at the hospital.
A personal assistant of another senior doctor too was detained by police on Friday and the nephrologist's role is under scanner now.
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The name of the third doctor emerged after the police came across a donor linked to the racket. The suspicion of his involvement grew after his name cropped up during Rao's interrogation. Police are already investigating his assistant's role, the official added.
Similar notices were earlier issued to five senior officials of the hospital, including the head of the 10-member internal assessment committee for transplant surgeries.
Twelve rpt twelve people, including two personal assistants of a nephrologist, several middlemen and donors, besides the kingpin have been arrested in connection with the racket so far.