It shall be the duty of the county attorney or authorized attorney when a copy of the finding of investigation or the application for financial assistance has been filed with him or her as provided in section 43-512, or when an application has been made pursuant to section 43-512.02, to immediately take action against the nonsupporting parent or stepparent of the dependent child. It shall be the duty of the county attorney or authorized attorney to initiate a child support enforcement action. If the county attorney initiates an action, he or she shall file either a criminal complaint for nonsupport under section 28-706 or a civil complaint against the nonsupporting parent or stepparent under section 43-512.03. If the attorney who initiates a child support enforcement action is an authorized attorney, he or she shall file a civil complaint against the nonsupporting parent or stepparent pursuant to section 43-512.03.