I suggest that you get it from the horses mouth. No, don't go visiting criminals in jail, try the Ann Arbor Police. Their phone number is 734/ 944-2875.
How soon are you moving to Ann Arbor? If you have time I suggest subscribing to the Ann Arbor Observer. They are a monthly periodical that contains a great looking map of reported crime every issue and it compares with the prior year.
They might have archives for overlays... (?) .
Good luck and let me know what you find.