Once you have read all the files, I am sure you'd have discovered a number of problems with the case. My recommendation is to take some notes down as you go through the files a second time. Ask yourself: What seems out of place, What is not accurate, what is out of order? Once you are done with the notes, you can group them in order of the different requirements for the assignment. You can expand on each of your notes by synthesizing some of references from the weekly lectures and assigned material. This should help you put together a good audit report that addresses the necessary points