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.