Mo. Rev. Stat. § 442.300
Current with changes from the 2024 Legislative Session
No proof, by evidence of the handwriting of the party and of a subscribing witness, shall be taken, unless the court or officer taking the same shall be satisfied that all the subscribing witnesses to such instrument are dead or cannot be had to prove the execution thereof.
§ 442.300, RSMo
RSMo 1939 § 3421