A person commits a crime of the fourth degree if, believing that an official proceeding or investigation is pending or about to be instituted, he:
(1) Alters, destroys, conceals or removes any article, object, record, document or other thing of physical substance with purpose to impair its verity or availability in such proceeding or investigation; or
(2) Makes, devises, prepares, presents, offers or uses any article, object, record, document or other thing of physical substance knowing it to be false and with purpose to mislead a public servant who is engaged in such proceeding or investigation.