Whenever it appears by the affidavit of the plaintiff, or by the return of the attachment, that no property is known to the plaintiff or the officer on which the attachment can be executed, or not enough to satisfy the plaintiff's claim, and it being shown to the court by affidavit that the defendant has property within the state not exempt, the defendant may be required to attend before the court in which the action is pending, or a commissioner appointed for that purpose, and give information on oath respecting the defendant's property.
Iowa Code § 639.34