FolderSizes search and scan filter rules can match files and folders by owner.
Use patterns in the form of domain\username. For example, to find files belonging to the username "administrator" in any domains, use the pattern "*\administrator" (without the quotes). Owner name match patterns are not case sensitive.
Tip: You can use the keyword "Unknown" to find file system objects with indeterminate ownership (e.g. an owner cannot be determined).
Note: Using the file owner matching feature can slow search operations considerably.
See also: Scan filter rules, Search rules