Mo. Rev. Stat. § 492.350: Certificate of officer taking depositions.

To every deposition or examination, taken by virtue of sections 492.080 to 492.400 shall be appended the certificate of the person or officer by or before whom the same shall be taken, showing that the deposition or examination was reduced to writing in his presence, and was subscribed and sworn to by the witnesses, and the place at which, and the days, and within the hours, when the same was taken.