All outstanding liability of relatives for the support of any patient or resident in a benevolent institution under the control of the department of mental health and addiction services or the department of developmental disabilities accrued prior to January 1, 1956, including the liability of the patient personally, is hereby canceled, provided that this section does not abrogate any written agreements or security arrangement for the payment of support charges entered into between the state and any patient or liable relative prior to such date.
R.C. § 5121.051