(a) In a case arising under this article or involving the Hague Convention on the Civil Aspects of International Child Abduction, the district attorney may take any lawful action, including resort to a proceeding under this part or any other available civil proceeding to locate a child, obtain the return of a child, or enforce a child custody determination if there is:

(1) An existing child custody determination;

(2) A request to do so from a court in a pending child custody proceeding;

(3) A reasonable belief that a criminal statute has been violated; or

(4) A reasonable belief that the child has been wrongfully removed or retained in violation of the Hague Convention on the Civil Aspects of International Child Abduction.

(b) A district attorney acting under this Code section acts on behalf of the court and may not represent any party.