Notwithstanding the provisions of section 622.72 , reasonable compensation as determined by the court shall be awarded expert witnesses, expert witnesses for an indigent person referred to in section 815.4 , or expert witnesses called by the state in criminal cases. [C79, 81, §815.5 ] 93 Acts, ch 175, §22 ; 99 Acts, ch 135, §25 ; 2013 Acts, ch 90, §211 Witnesses for indigents, see R.Cr.P. 2.20(4)