Description:  An individual employee may be the custodian of ESI located on his/her local computer(s), hard drives, media as well as specific network storage locations under their sole administrative control. Even though a member of the IT department is usually the administrator of email and other systems, the ESI from some of these systems is still associated with the individual custodian. For example the user's mailbox, phone messages and more. the volume and types of ESI associated with a custodian will vary by department and position.