R&B star Rihanna is cooperating with investigators building a domestic violence case against her boyfriend, the singer Chris Brown, a police source said Monday. The source said the 20-year-old performer, whose full name is Robyn Rihanna Fenty, was providing “ongoing” cooperation to detectives who booked Brown on Sunday on suspicion of making criminal threats against her. An early morning altercation with Brown after a pre-Grammy Awards party left Rihanna with bruises and a scratch on her face, according to police sources. She was treated at a “major medical facility,” a police source said. Read more over at Los Angeles Times.