The coroner may issue subpoenas for witnesses returnable forthwith or at such time and place as the coroner may appoint, which may be served by any competent person. The coroner must summon and examine as witnesses, on oath administered by the coroner, every person, who, in his or her opinion or that of any of the jury, has any knowledge of the facts. A witness served with a subpoena may be compelled to attend and testify, or be punished by the coroner for disobedience, in like manner as upon a subpoena issued by a district judge.