622.71  Peace officer.
  No peace officer who receives a regular salary, or any other public official shall, in any case, receive fees as a witness for testifying in regard to any matter coming to the officer’s or official’s knowledge in the discharge of the officer’s or official’s official duties in such case in a court in the county of the officer’s or official’s residence, except police officers who are called as witnesses when not on duty.
[C97, §4661; C24, 27, 31, 35, 39, §11328; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §622.71]