The attorney general may offer to a county or district attorney the assistance of the attorney general's office in the prosecution of an offense described by Article 66.102(h) the victim of which is younger than 17 years of age at the time the offense is committed. On request of a county or district attorney, the attorney general shall assist in the prosecution of an offense described by Article 66.102(h) the victim of which is younger than 17 years of age at the time the offense is committed. For purposes of this article, assistance includes investigative, technical, and litigation assistance of the attorney general's office.
Tex. Code Crim. Proc. § 2.021