The data owner is the person who has the authority and responsibility to classify, grant access, and monitor the use of the CRM data. The data owner should ensure that the data is protected according to its classification and business requirements. The data custodian is the person who implements the controls and procedures to protect the data as directed by the data owner. The information security manager is the person who advises the data owner on the best practices and standards for data security. The internal IT audit is the function that evaluates the effectiveness and compliance of the data security controls and procedures.
References = CISM Review Manual, 16th Edition eBook1, Chapter 1: Information Security Governance, Section: Information Security Roles and Responsibilities, Subsection: Data Owner, Page 23.