A University of Southern California student will not face charges for the fatal stabbing of a homeless man he said was done in self-defense.

Ivan Gallegos, 19, was arrested on suspicion of murder Monday night in the death of 27-year-old Xavier Cerf.

Police said Gallegos saw Cerf breaking into his car in the parking lot behind his fraternity house on Monday night. According to police, Cerf told him he had a gun, at which point the student stabbed him.