citrix xen servers and user profiles

we have a large thin client infrastructure whereby users use wyse terminals to access citrix xenapp servers for desktops/applications. Our security team often require copies of users profiles for investigation purposes. On laptops all this information remains intact. But the citrix team inform me that these profiles (i.e. c:\users\..) are cleaned from the citrix servers routinely and therefore this evidence doesnt exist for long.

What is this process of cleaning users profiles off your citrix servers typically referrred to as? And why do admins do it? We have a large workforce of over 2000 users. is it common to redirect the profile elsehwere, like a home drive server, or is it just common that this info probbaly isnt required and to delete it from the citrix servers routinely.