New details surrounding Diane Keaton's death are being revealed. A death certificate obtained by People on Thursday, October 16, confirmed that primary bacterial pneumonia was Keaton's immediate cause of death and that she had the illness for days before her death. She was 79. The document doesn't list significant contributing conditions and says Keaton was cremated on Tuesday, October 14. The news comes just one day after the Keaton family spoke out about the late Oscar winner and revealed her cause of death.