Mr. Mohammed was the last of about 500 Indians whose kidneys were removed by a team of doctors running an illegal transplant operation, supplying kidneys to rich Indians and foreigners, police officials said. A few hours after his operation last Thursday, the police raided the clinic and moved him to a government hospital.

Many of the donors were day laborers, like Mr. Mohammed, picked up from the streets with the offer of work, driven to a well-equipped private clinic, and duped or forced at gunpoint to undergo operations. Others were bicycle rickshaw drivers and impoverished farmers who were persuaded to sell their organs, which is illegal in India.

Although several kidney rings have been exposed in India in recent years, the police said the scale of this one was unprecedented. Four doctors, five nurses, 20 paramedics, three private hospitals, 10 pathology clinics and five diagnostic centers were involved, Mohinder Lal, the police officer in charge of the investigation, said.

“We suspect around 400 or 500 kidney transplants were done by these doctors over the last nine years,” Mr. Lal, the Gurgaon police commissioner, said.