Utah Code § 77-30-14: Arrest without warrant.

The arrest of a person may be lawfully made also by any peace officer or a private person without a warrant upon reasonable information that the accused stands charged in the courts of a state with a crime punishable by death or imprisonment for a term exceeding one year, but when so arrested the accused person must be taken before a judge or magistrate with all practicable speed and complaint must be made against the accused person under oath setting forth the ground for the arrest as in Section 77-30-13, and thereafter the accused person's answer shall be heard as if the accused person had been arrested on a warrant.