At some point, Harnett gained weight and underwent a mastectomy. Due to health concerns, she was later placed in a home for long-term care. According to fellow 1950s Ford model Betsy Pickering, Gerald W. ″Jerry″ Ford, founder of Ford Models, hospitalized Harnett for mental illness. Harnett died from injuries sustained in a fire at the home in May 1987 when she was 63.
