Tennessee Code Title 40. Criminal Procedure § 40-14-207

(a) Other than public defenders and post-conviction defenders, attorneys appointed under this part shall be entitled to reasonable compensation for their services prior to trial, at trial, and during the appeal of the cause and shall be entitled to reimbursement for their reasonable and necessary expenses in accordance with the rules of the supreme court.

(b) In capital cases where the defendant has been found to be indigent by the court of record having jurisdiction of the case, the court in an ex parte hearing may, in its discretion, determine that investigative or expert services or other similar services are necessary to ensure that the constitutional rights of the defendant are properly protected. If that determination is made, the court may grant prior authorization for these necessary services in a reasonable amount to be determined by the court. The authorization shall be evidenced by a signed order of the court. The order shall provide for the reimbursement of reasonable and necessary expenses by the administrative director of the courts as authorized by this part and rules promulgated thereunder by the supreme court.