NICKSERV INFO

Usage: NICKSERV INFO <nick>

This will show the information on a nick including fields that can only be seen by opers, such as marks.

Example:
/msg nickserv info Jennifer

Whenever you do an info command while opered, you will see the additional information available to opers. Whenever you're working with a nick, it is generally a good idea to check its info just in case it shows you something useful.