The Perfect Nanny (2000)

Upon her release from a mental institution where she was recovering from a suicide attempt, Andrea McBride applies for the position of nanny for a handsome, wealthy surgeon, Dr. James Lewis, a widower with two children. Another applicant is hired, but she dies in an accident and Andrea gets the job after all, excelling and quickly becoming part of the family. Then Lewis' girlfriend, Dr. Julia Bruning, is mysteriously killed. When his boss tells Lewis of impending cutbacks at the hospital, the boss is murdered. Meanwhile, Lewis' teenaged daughter Fawn begins piecing together the history of the new nanny and discovers that Andrea may be responsible for these and other killings - but Fawn had better hurry, because the slayings are getting closer to home