Mo. Rev. Stat. § 106.290: Payment of costs.

If, upon the trial of such cause, the defendant be acquitted, the complainant shall be adjudged to pay all costs, and upon motion for that purpose, filed before said cause shall be called for trial, the court may compel him to give security for payment of the same, and in default thereof may dismiss the complaint, except that in cases where the complaint is filed officially, no security for costs shall be required, and no costs adjudged against the complainant; but the same shall be paid by the county in case of acquittal, and by the defendant in case of conviction.