Upon receipt of a report or complaint as provided in § 17a-412, the Commissioner of Social Services shall determine immediately whether there are reasonable grounds for an investigation. If it is determined that reasonable grounds do not exist for an investigation, the complainant or the person making the report shall be notified of this determination not later than five working days after the receipt of such complaint or report. If such reasonable grounds are found, the Commissioner of Social Services shall investigate such report or complaint not later than ten working days thereafter. The Commissioner of Social Services shall complete an investigation and make a report of the findings not later than fifteen working days after the receipt of the complaint or report. If the investigation indicates that there is a possible violation of § 19a-533, 19a-535 or 19a-537, the Commissioner of Social Services shall refer the report or complaint together with a report of any investigation the commissioner has undertaken to the Department of Public Health for action as appropriate. If the investigation indicates that there is a possible violation of the provisions of the Public Health Code with respect to licensing requirements, the Commissioner of Social Services shall refer the report or complaint, together with a report of the investigation, to the Commissioner of Public Health for appropriate action. If no violation of the Public Health Code is indicated, the Commissioner of Social Services shall take whatever action said commissioner deems necessary, and shall notify the complainant or the person making the report, of the action taken not later than fifteen working days after receipt of the complaint or report. If the investigation indicates that a person has abused, neglected, exploited or abandoned a resident in a long-term care facility, the Commissioner of Social Services shall refer such information in writing to the Chief State’s Attorney or the Chief State’s Attorney’s designee who shall conduct such further investigation, if any, as deemed necessary and shall determine whether criminal proceedings should be initiated against such person in accordance with applicable state law.