Who is Simone Orr from 'I' Is for Innocent and what is their importance?

Simone Orr is Isabelle's sister. She helped Isabelle through three marriages and multiple career changes. She cares for her so often, in fact, that she has moved into a cottage on Isabelle's property. Before Isabelle's death, she had a drinking problem. On the night she died, Simone found her body with a couple of Isabelle's friends who had come to pick her up for a trip to San Francisco. Simone immediately blamed David Barney.