In IL, who should I sue to obtain my security deposit if the unit was being managed by a realty group on behalf of the owner?

After some last minute contention between the realty agent and myself, the agent conducted a walk-through of the unit when I was not present, and she did not wish to accommodate. Anticipating some trouble, I took pictures prior to handing over the keys and had 2 independent witnesses sign to attest to the conditions of the unit on that day. She recently submitted a report (1 week after lease expired) which claims multiple conditions were unsatisfactory, and will lead to deductions from the full return of my deposit. This includes disinfecting the counters, cleaning windowsills, etc. I have ceased communication temporarily with agent and owner as I seek advice on how to proceed. I do not have any of the owner's contact information as all matters went through the agent.