New Jersey Statutes Title 54. Taxation 54 § 1-19

In making the investigation upon such written complaint the Director of the Division of Taxation may examine any assessor under oath, as to his assessments, both as to the valuation as a whole and as to any particular piece of property or as to any property omitted from assessment, and inquire by the testimony of witnesses concerning the same. If he shall deem it proper, he may make a personal examination of any property in a taxing district or county, for the purpose of equalizing assessments between districts or between counties bearing a common burden of taxation.