The Staircase Michael Peterson's Family Tree
The Staircase: A Complete Breakdown of the Peterson Family
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Michael adopted Margaret (far left) and Martha (middle) after their mother, Elizabeth Ratliff, passed away in Germany from what was thought to be a cerebral hemorrhage. Like Kathleen, Elizabeth was found at the bottom of a staircase with lacerations on the back of her head, with Michael being the last person to see her alive. Margaret and her sister Martha immediately took to Kathleen, and they refer to her as their mother in the series. Like her sister and adoptive brothers, Margaret is convinced that her father is innocent.
A graduate from Columbia College in Chicago, she now resides in California and goes by her married name, Margaret Blakemore. According to IMDb, she works in the film industry and has credits as an actress, production manager, and assistant director.