Mo. Rev. Stat. § 544.376
At any preliminary hearing conducted in the courts of this state, a report from any crime laboratory in the state, or from any federal crime laboratory, relating to the testing, analysis, identification, or comparison of evidence and certified under the seal of that laboratory shall be received into evidence on the issue of the results of scientific tests. The accused or his attorney of record shall be provided with a copy of such report at least ten days prior to the preliminary hearing and shall have the opportunity before the hearing upon notice to the state of the time and place to conduct the interview, which may be recorded, of any person who conducted the testing, analysis, identification, or comparison of evidence which is the subject matter of the report. Nothing in this section shall affect the right of the accused to subpoena such person.
§ 544.376, RSMo