How to find out who is deleting files on a Linux server?

view story

http://serverfault.com – We have a Linux server which is Ext4 and another Linux Server which has an ISCSI where Windows clients have shared folders.I need to Allow users to modify files and not delete them. A user has permission to modify content, but cannot delete the files itself. Audit all file add/delete/modify operations in a English like log format. Send alerts if attempts are bieng made to delete (HowTos)