When did Martha Alice hageman die?

Answer 1

The best anyone can give about that question is an approximation. Sybil was approximately 26 years old when she mentioned to her psychiatrist Cornelia Wilbur that her mother had died "a while back." Her father re-married around the time Sybil made this comment. Sybil's mother was over 40 when she had Sybil but no one is certain how much older. Based on Sybil's age and her vague referral to Martha's death she probably died in her mid to late 60's.