Mo. Rev. Stat. § 210.127: Diligent search for biological parents required, when.

1. (1) If the location or identity of the biological parent or parents of a child in the custody of the division is unknown, the children's division shall conduct an active, thorough, and timely diligent search for the biological parent or parents of such child, including obtaining information from any known parent or relative.

(2) If a child is removed from a home and is placed in the custody of the division, the division shall, immediately following the removal from the home, conduct an active, thorough, and timely diligent search for the biological parent or parents, including obtaining information from any known parent or relative.

2. For purposes of this section, "diligent search" means an exhaustive effort to identify and locate a biological parent whose identity or location is unknown, initiated as soon as the division is made aware of the existence of such parent, with the search progress reported at each court hearing until the parent is either identified and located or the court excuses further search.