Mo. R. Crim. P. 26.04
A judge shall have power, upon the application of any party to a criminal proceeding pending in such court, to issue a writ of habeas corpus for the purpose of bringing before such court any person who may be detained in jail or prison, or who may be otherwise in custody, to be a witness on behalf of the applicant. The application shall state that the testimony of such witness is material and necessary to the applicant on the trial or any hearing in such criminal proceedings.
Mo. R. Crim. P. 26.04
Committee Note-1979
The source is prior Rule 25.16. The rule has been expanded to include persons in mental hospitals, mental institutions, and in custody of juvenile officials. The last sentence of Rule 25.16 requiring verification has been deleted.