Iowa Code Title XV. Judicial Branch and Judicial Procedures [Chs. 595-686] § 622.78. Serving subpoena

If a witness hides, or in any manner attempts to avoid being personally served with a subpoena, any sheriff having the subpoena may use all necessary and proper means to serve the same, and may for that purpose break into any building or other place where the witness is to be found, having first made known the sheriff's business and demanded admission.