Mo. Rev. Stat. § 211.111: Summons, how served.

1. Service of summons shall be made personally by the delivery of an attested copy thereof to the person summoned. But if the juvenile court is satisfied after thorough investigation that it is impracticable to serve the summons personally, it may order service by registered mail to the last known address of the person or by publication.

2. Personal service shall be effected at least twenty-four hours before the time set for the hearing. Registered mail shall be mailed at least five days before the time of the hearing.

3. Service of summons may be made by any suitable person under the direction of the court.