The coroner may perform an autopsy in any death case or cause one to be performed by a competent physician. He shall do so:
(1) When there is a reasonable probability that the violation of a criminal statute has contributed to the death;
(2) When ordered by the court, which order may be issued ex parte by the court either on its own motion or on application by the district attorney; or
(3) In all other cases provided by law.
Acts 1987, No. 878, §2.