Mo. Rev. Stat. § 140.115

Any person other than the owner or a mortgagee or other lienholder described in section 139.070 who pays the original taxes, as charged against the tract of land or town lot described in the back tax book, together with interest from the day upon which the tax first became delinquent at the rate specified in section 140.100 shall not invoke a lien on said property or person without the knowledge and consent of the owner. Any such lien so invoked on said property or person without the knowledge and consent of the owner shall be null and void.