More like, you can bet all schools do this. A university puts itself in immense legal liability when they hire new employees and admit new students. Can you imagine the lawsuits that'll appear if a university unknowingly (but should have not, via background check) admit a person with history of rape and an employee there gets raped? That's millions of dollars down the drain. You can bet that university's lawyers won't be so sloppy as to not force the univ to not do a background check.
Once they do a background check (and they will do one) and something comes up, a committee gets together to decide what to do. If they decide it's not major, they let it go. Otherwise, they'll decide to let the student/employee go. If a certain student has something on his record and is enrolled in the school, what's happened is that the school decided it's okay for him to be enrolled, not that they didn't do a background check and doesn't know. They absolutely know.