New Jersey Statutes Title 40. Municipalities and Counties 40 § 41A-49

The office of county manager shall be deemed vacant if: the incumbent moves his residence from the county without board permission; or he is by death, physical or mental illness or other casualty unable to continue to serve as county manager. Any vacancy in the office of county manager shall be filled in the manner prescribed in section 47 of this article.  1 The board of freeholders may appoint the deputy manager or any department head to serve as acting county manager until a successor has been appointed. During the temporary absence or temporary disability of the county manager the deputy manager or a department head designated by the manager if there be no deputy manager, shall serve as acting county manager.