Tenant left @ end of lease, but has unpaid rent - modified renter

[Patrick Gallagher]

Hi all, this is my first post so will try not to botch it.

Also first time real estate investor and first time landlord. Teamed up with my fiancée. We just recently closed on a duplex in Cleveland, Ohio a few months ago. 

Inherited tenant has unpaid rent, and had put down a $1200 sec. deposit at the beginning of his lease. The unpaid rent is more than the $1200 but not by all that much. We were in the eviction process when the tenant's lease term expired and he finally agreed to go. He left today and our GC went by to verify and actually took the keys from him so thank goodness for that. We don't want to take him to courst for unpaid rent or anything like that. The amount is not that high. 

Our GC took a quick look today and it doesn't look like they did any real damage to the unit, tenant also sent us a walkthrough video and property was in surprisingly clean and spartan condition. 

I'm thinking we are totally in the clear to not return the security deposit, and I'm thinking that we still obv. need to do our walkthrough but will be keeping all sec. deposit anyway. Guess just looking for some guidance. I don't have tenant's next place of residence. Am I required to mail some kind of notice/breakdown of his final balance, why he's not getting deposit back?

Just really, any tips/guidance for this exact situation would be very much appreciated.