A nine-month investigation by the Center for Public Integrity has found that a thick blanket of secrecy envelops cases involving allegations of sexual assault on campus. Many victims don’t report at all, and those who do come forward can encounter secret disciplinary proceedings, closed-mouthed school administrations, and off-the-record negotiations. At times, school policies and practices can lead students to drop complaints, or submit to gag orders — a practice deemed illegal.