MO Rev Stat § 552.060 (2021)
2021 Missouri Revised Statutes|Title XXXVII - Criminal Procedure|Chapter 552 - Criminal Proceedings Involving Mental Illness|Section 552.060 - Mental disease or defect upon sentence to death.

Effective - 28 Aug 1989   552.060. Mental disease or defect upon sentence to death. — 1. No person condemned to death shall be executed if as a result of mental disease or defect he lacks capacity to understand the nature and purpose of the punishment about to be imposed upon him or matters in extenuation, arguments for executive clemency or reasons why the sentence should not be carried out.  2. If the director of the department of corrections has reasonable cause to believe that any inmate then in confinement in a correctional facility and sentenced to death has a mental disease or defect excluding fitness for execution, he shall immediately notify the governor who shall forthwith order a stay of execution of the sentence if there is not sufficient time between such notification and time of execution for a determination of the mental condition of such person to be made in accordance with the provisions of this section without such stay. The director shall also, as soon as reasonably possible, notify the director of the department of mental health and the prosecuting or circuit attorney of the county where the defendant was tried, the attorney general and the circuit court of the county where the correctional facility is located.  3. As soon as reasonably possible, after the notification prescribed in subsection 2 of this section, the circuit court of the county shall conduct an inquiry into the mental condition of the offender after first granting any of the parties entitled to notification an examination by a physician of their own choosing on proper application made within five days of such notification.  4. If the court, after such inquiry, certifies to the governor and to the director that the prisoner does not have a mental disease or defect of the type referred to in subsection 1 of this section, the governor shall fix a new date for the execution, if a stay of execution had previously been made, and shall issue a warrant for the new execution date to the chief administrative officer of the correctional facility, who shall then proceed with the execution as ordered. If the court, after such inquiry, certifies to the governor and to the director that the prisoner has a mental disease or defect of the type referred to in subsection 1 of this section, the offender shall not be executed but shall be held in the correctional facility subject to transfer to a mental hospital and further proceedings under section 552.050 if the provisions of section 552.050 are applicable. If any offender who has not been executed because of any certification by the director as herein provided is thereafter certified by the director as free of a mental disease or defect of the type referred to in subsection 1 of this section, the governor shall fix a new date for the execution and shall issue a warrant for the new execution date to the chief administrative officer of the correctional facility, who shall then take charge and custody of the offender and proceed with the execution as ordered in the warrant.  5. Nothing in this chapter shall be construed to limit the governor or any court in the exercise of any of their powers in any other manner under the law or Constitution of Missouri. ­­-------- (L. 1963 p. 674 § 6, A.L. 1989 H.B. 408)