A group of doctors at Rush University Medical Center’s prestigious orthopedic department routinely overbooked their schedules and relied heavily on residents to perform surgeries, violating federal Medicare billing rules, according to a newly unsealed whistle-blower lawsuit filed in U.S. District Court in Chicago.

The suit alleges that in one instance, a surgeon never entered the operating room to supervise a procedure. In others, a surgeon monitored residents performing operations via video feed while simultaneously performing his own operations in nearby rooms.