CHICAGO (AP) -- Classes at Chicago's St. Xavier University will resume this week after threatening graffiti closed campus for several days.

University President Judith Dwyer says all the school's campuses will reopen Wednesday and graduate classes will resume Wednesday night.

Undergraduate classes will start up again Thursday morning. But any students who can't return to class before Monday won't be penalized academically.

The graffiti found last week in a St. Xavier bathroom read "Be prepared to die on 4/14." That caused the school to shut down indefinitely Friday.

The investigation into who wrote the graffiti continues. But according to the university, law enforcement officials found nothing that indicates the existence of a continuing viable threat.