If it appears from the examination of any commercial fertilizer that any of the provisions of this part or the rules and regulations issued under this part have been violated, the commissioner shall cause notice of the violations to be given to the registrant, distributor, or possessor from whom the sample was taken; any person so notified shall be given an opportunity to be heard under such rules and regulations as may be prescribed by the commissioner. If it appears after the hearing, either in the presence or absence of the person so notified, that this part or rules and regulations issued under this part have been violated, the commissioner may certify the facts to the proper district attorney general.