New Jersey Statutes Title 54. Taxation 54 § 5-91

Any person whose interest in the lands cannot, in the exercise of reasonable diligence, be ascertained from the search of the title of the premises described in the certificate of sale, made of the indexes in the office of the surrogate and county clerk or register of deeds and mortgages in the county in which the lands are situate, and in the office of the Secretary of State, extending back sixty years next preceding the date of the sale, shall be deemed to be included in the term “unknown owner” or “unknown claimant.”