PARK CITY, Utah  — Mary J. Blige is lending her support — and her voice — to a documentary showing at the Sundance Film Festival about sexual assault in the U.S. military.

Blige attended the Friday world premiere of "The Invisible War." Producer Amy Ziering says the multiple Grammy winner would write an original song for the film after the Sundance festival.

Blige's song, "Need Someone," plays over the closing credits of the film.

Written and directed by Kirby Dick, "The Invisible War" examines the trauma suffered by female and male victims of rape at the hands of their military colleagues and the difficulty they have in prosecuting their attackers.

Sen. Barbara Boxer of California, U.S. Rep. Jackie Speier, Lt. Gov. Gavin Newsom and U.S. Rep. Mike Turner of Ohio also attended the premiere.