“We used to see very serious abuse of women and children quite often,” he said, noting that the city was still struggling to absorb an influx of refugees after the civil war in what was East Pakistan, now Bangladesh.

“I never even saw any nuns in those slums that I worked in,” he said. “I think it’s an imperialist venture of the Catholic Church against an Eastern population, an Eastern city, which has really driven horses and carriages through our prestige and our honor.

“I just thought that this myth had to be challenged,” he added.

Over hundreds of hours of research, much of it cataloged in a book he published in 2003, Dr. Chatterjee said he found a “cult of suffering” in homes run by Mother Teresa’s organization, the Missionaries of Charity, with children tied to beds and little to comfort dying patients but aspirin.

He and others said that Mother Teresa took her adherence to frugality and simplicity in her work to extremes, allowing practices like the reuse of hypodermic needles and tolerating primitive facilities that required patients to defecate in front of one another.

But it was not until he moved to the United Kingdom in 1985, eventually taking a job in a rural hospital, that he realized the reputation Kolkata had acquired in Western circles.

In 1994, Dr. Chatterjee contacted Bandung Productions, a company owned by the writer and filmmaker Tariq Ali. What started as a 12-minute phone pitch turned into an offer by Channel 4’s commissioning editor to film an exposé of Mother Teresa’s work. The social critic Christopher Hitchens was hired to present what would become “Hell’s Angel,” a highly skeptical documentary.

Over the next year, Dr. Chatterjee traveled the world meeting with volunteers, nuns and writers who were familiar with the Missionaries of Charity. In over a hundred interviews, Dr. Chatterjee heard volunteers describe how workers with limited medical training administered 10- to 20-year-old medicines to patients, and blankets stained with feces were washed in the same sink used to clean dishes.