Tenn. Code Ann. § 68-102-129

If, after examination of witnesses or any investigation, the commissioner, or any of the commissioner's deputies or assistants, is of the opinion that the facts in relation to a fire indicate that a crime has been committed, the commissioner shall present the testimony taken on examination, together with any other data in the commissioner's possession, to the district attorney general of the county in which the crime has been committed, and the district attorney general shall call especially to the attention of the grand jury such testimony, and if the facts warrant an indictment, no prosecutor shall be required.