When the “Varsity Blues” admissions bribery scandal broke in March, USC declared itself as a victim of fraud, asserting it had no reason to believe that senior administrators were aware of the wide-ranging scam, which helped unqualified students gain entry to USC by way of bogus application materials. Now, new details about Donna Heinel, the senior associate athletic director who prosecutors say was a key conduit in the scheme, shed light on just how expansive her role within the athletics department was — and on whether USC monitored her activities closely enough.