A summons may be issued by a law-enforcement officer during the course of his immediate investigation of an alleged misdemeanor for which an arrest warrant is not required pursuant to § 19.2-81 to any person he reasonably believes was a witness to the offense. The summons shall command the person to appear and testify at the trial of any criminal charge brought against any person as the result of the offense. A summons issued pursuant to this section shall have the same force as if issued by the court. The failure of any person so summoned to appear after receiving written notice of the date, time and place of the trial at least five days prior to the trial shall be punishable as contempt of the court in accordance with § 18.2-456 (5).