Atlanta ? Coretta Scott King’s four children talked about her last days Sunday, saying she had appeared to be making steps toward recovery before she died suddenly the day she was supposed to begin treatment at an alternative medical clinic in Mexico.

“It came as a tremendous shock to us. We had no idea,” eldest daughter Yolanda King said at a news conference. “She was walking with a cane, she was speaking more words … there was clearly progress happening.”

Coretta Scott King, 78, died Monday from pneumonia brought on by complications caused by ovarian cancer. Her grieving children said an autopsy showed the cancer, diagnosed in November, had been growing in her body for a year and a half.

Yolanda King said she and her siblings made the decision to send their mother to the alternative clinic, which Mexican authorities shut down days after King’s death, saying it had carried out unproven treatments and unauthorized surgeries. The clinic’s director has a criminal past and a reputation for offering dubious treatments.

Yolanda King, however, said the family had thoroughly researched the clinic.

“We were stunned when we found out there were problems and challenges there,” Yolanda King said. “They came highly recommended. We made the decision to go there and Mother concurred because we believed the place was doing incredible work.”

Bernice King, the only one of King’s children who was with her mother in her final days, said her mother spent her last weekend under observation at the clinic.

Son Dexter King choked back sobs as he explained that his mother died on his birthday, but added that he now finds a little comfort in that.

“She chose to go home on the day she gave birth to you,” Dexter King said a friend told him. “I’m able to celebrate her life, what she gave to the world.”

Bernice King, a minister at New Birth Missionary Baptist Church, will deliver her mother’s eulogy there on Tuesday.