Tenn. Code Ann. § 16-2-521

The number of criminal investigator positions to which the district attorney general of each judicial district is entitled pursuant to § 16-2-506 or any other law shall be the minimum number of positions authorized in each judicial district. No law shall be construed to prohibit the employment of additional criminal investigators in a judicial district as established by § 16-2-506, regardless of whether the positions are funded by a state or non-state source, or whether they are specifically enumerated in any other law.