Who enrolled a user into an enrollment

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This maybe a Monday afternoon brain drain, but how do I find out who enrolled a user into an enrollment?  I tried various different Audit Reports in BI but none seem to work.  

We have carefully assigned people to various groups and those groups to learning plans and used categories and areas in a page to only allow people to self register for classes they are allowed to take.  

Lo and Behold I find out that some of our data entry users who have Control Panel/Enrollment rights are registering people into enrollments via the Control Panel.  I really need to get a handle on this but don't want to blanket the group when it is one or two people.  How do I find out????