Mo. Rev. Stat. § 493.130

It shall be unlawful for any officer of the law, attorney at law, administrator, agent or person holding property in trust, to make a profit, directly or indirectly, through or by virtue of any contract, express or implied, made with any newspaper or publishing company for any advertisements, official or otherwise, and any rebate contracted for, allowed or given to such officer, attorney or person shall be accounted for, and the benefit thereof given to the party entitled thereto.