The image shows welts on the 20-year-old's forehead above each of her eyebrows, marks on her cheek and bleeding around her lips.
Los Angeles police have now launched an investigation to find how the image was leaked to TMZ.
Brown, a multi-platinum selling singer, allegedly attacked Rihanna, 20, on February 8 in Los Angeles after a pre-Grammy's party. He was arrested shortly after.
TMZ
