If the enforcing officer determines from his investigation that a public nuisance
exists, he shall serve or cause to be served, either by personal service or by registered
or certified mail, a copy of a notice of vehicle abatement upon every person concerned,
including the owner of the property on which the alleged public nuisance exists, as
shown on the last equalized assessment roll, and the last known registered and legal
owner of the subject vehicle if the identification numbers are available to determine
ownership. If a notice sent by registered or certified mail is returned unclaimed,
a subsequent notice sent by first class mail, postage prepaid, to the last known address
of the party concerned shall be sufficient and such notice shall be effective upon
mailing. The failure of any person to receive such notice shall not affect in any
manner the validity of the proceedings taken hereunder.