The notice shall be served upon the owner, tenant or other person responsible for the condition by personal service, registered mail or certified mail with return receipt requested, addressed to the last known address of such person. If, after a reasonable search and reasonable efforts are made to obtain service, the whereabouts of the person is unknown or service cannot be accomplished and the planning director makes an affidavit to that effect, then service of the notice upon such persons may be made by:
1. Publishing the notice once each week for two consecutive weeks in the town's official newspaper; and
2. Mailing a copy of the notice to each person named on the notice of violation by first class mail to the last known address if known, or, if unknown, to the address of the property involved in the proceedings.