Can I Use Security Deposit of a Legacy Tenant

[Victor Olowu]

A tenant that came with the building I just bought a year ago will be moving out in a few days, but there is no real way to figure out how much of the damage (non-normal wear and tear) on the unit is caused by the tenant since I don't know the unit's state when they moved in.  These are things I don't believe the old landlord would have left unattended before renting the unit out to her, like cracked/loose countertops and broken closet doors.  I did a walkthrough of the units in the building before and after closing on the property, and most of the damages were there then as well, but she's been there 3 years now.

Knowing that Chicago is very tenant-friendly, especially when it comes to security deposits, makes me want to just give her back her entire deposit and cut my losses, or is there any other way to sort this out.