Michelle is one of the main characters. Her death is what sets Max Payne on his journey to get revenge on those who are responsible for it.
She was a part-time D.A. where she came upon the project Valhalla documents that Alfred Woden had sent to incriminate Nicole Horne.
Nicole then sent V-head junkies to kill Michelle and the rest of the Payne family.
The player can hear her voice many times in-game only in the first level where the murder took place and several times again in the "nightmare levels"