But in recent days, the investigation has focused on the two packets of pills sent home with each patient after surgery, one containing ciprofloxacin, an antibiotic, and the other containing the anti-inflammatory and painkiller ibuprofen.

One clue pointing to the pills was another death and scores of hospitalizations from separate sterilization clinics overseen by another surgeon two days later. That surgeon, Dr. K. K. Sao, said there was a third set of patients as well, people who did not undergo surgery, but were given medicine from the same batches for other reasons. One such patient who died on Thursday was a 75-year-old man, he said.

State officials in the district have confiscated shipments of ciprofloxacin and ibuprofen.

Roopchand Siras, a barber from the village of Amsena whose wife died on Monday after undergoing sterilization, said health officials had “ordered that the medicines should be seized,” and came to his house to collect the remaining pills. Another resident, Bedan Bai, said her granddaughter began vomiting an hour after taking her first dose of ciprofloxacin and later died.

The Chhattisgarh state government said it had halted the distribution of drugs made by two Indian pharmaceutical companies, Medisafe Spirit and Medicare Spirit. “Complaints were received against the two companies for supplying substandard medicines,” a statement posted on Twitter by the state government said.