A hospital's Chief Medical Officer is formally accountable for the classification and permissible uses of patient health records. She has directed that these records be classified as 'Highly Confidential.' A database administrator on the IT operations team is tasked with configuring nightly backups, applying encryption, and managing access control lists on the storage array that holds these records. During an audit, a reviewer asks who is filling the data custodian role for these records. Who is the data custodian in this scenario?