Legal Question in Landlord & Tenant Law in Illinois

With such little information to go on, the best I can say is that you need to find out who the executor of his/her estate is. That person may or may NOT be responsible for dealing with security deposits. You may have some additional protection if your lease is covered by the Chicago Residential Landlord & Tenant Ordinance, but you don't even say if you already moved out or whether you are still a tenant.