Mo. Rev. Stat. § 140.450: Cancellation and filing of certificate — proof of loss.

When conveyances are delivered for lands sold for taxes the certificates therefor shall be cancelled and filed away by the collector; and in case of the loss of any certificate, on being fully satisfied thereof by due proof, or upon the production of a certified copy thereof, the collector may execute and deliver the proper conveyance, and file such proof in his office.