Tennessee Code Title 3. Legislature § 3-3-121

(a) Whenever a witness, summoned by subpoena issued as hereinbefore provided, fails to appear, or, having appeared, fails to answer, as provided in § 3-3-112, and the facts are reported to either house, the speaker of the senate or the speaker of the house of representatives, as the case may be or the chair of the committee in any event, shall certify such facts forthwith to the district attorney general for any county or counties in which such failing or refusing witness is subject to indictment and trial under this chapter, whose duty it shall be to bring the matter before the grand jury for its action, at the first opportunity, and to prosecute such offending witness by virtue of the office as such district attorney general, and is also the district attorney general's duty ex officio to prefer an indictment against such offending person.

(b) It is also the duty of the district attorney general for any county or counties in which any person or witness is subject to indictment and trial under §§ 3-3-113, 3-3-114 and 3-3-120, to bring the matter of any violations of those sections before the grand jury for its action, at the first opportunity, and to prosecute such offending person by virtue of the office as such district attorney general, and it is the district attorney general's duty ex officio to prefer an indictment against such offending person.