verified  with  the  Canal  Zone  Commission  is acceptable. 3. If the person claims U.S. citizenship by naturalization, a Certificate of Naturalization is required. A Certificate of Citizenship is required if the person claims to have derived U.S. citizen- ship through the naturalization of the parent(s). If  the  person  does  not  have  a  Certificate  of Citizenship, the Certificate of Naturalization of the parent(s) may be accepted if the naturaliza- tion occurred before the age of 18 (or before the age of 16 before 5 October 1978) and the person was a permanent U.S. resident. Certificates presented must be originals; making copies is illegal. 4. A U.S. passport issued to the person or one in which the person was included (that is, a child and  parent  on  a  passport  photograph)  is acceptable. PERSONNEL SECURITY INVESTIGATIONS Persons are given access to classified informa- tion or assigned to sensitive duties only if their loyalty, reliability, trustworthiness, and judgment is determined. The initial determination is based on  a  personnel  security  investigation  (PSI) appropriate to the access required or to other factors involving the sensitivity of the duties assigned. Although commanding officers may request PSIs on personnel under their jurisdiction, they may request only the minimum investigation to satisfy a requirement. The Defense Investigative Service (DIS) or, where specified, the Office of Personnel Manage- ment (OPM) conducts or controls all PSIs for the Department of the Navy. You are prohibited from conducting PSIs, including local public agency inquiries, without a specific request from DIS. Keep PSI requests to the absolute minimum. Do not use them as a means of identifying problem personnel security cases. Types of Personnel Security Investigations A personnel security investigation(PSI) is an inquiry by an investigative agency into a person’s activities conducted for the purpose of making a personnel security determination. Investigations conducted  for  other  purposes  may  affect  a person’s employment, clearance, or assignment, but are not PSIs. Examples are investigations of compromise, criminal activity, sabotage, espionage, or subversion. Because the Navy uses various levels of infor- mation, it must have a system of protecting all types of information that could jeopardize our national security. Some materials could have a more devastating effect on our nation than others. For that reason, the Navy conducts personnel security investigations before granting a security clearance to persons who handle sensitive infor- mation. These investigations fall into one of the seven  categories  described  in  the  following paragraphs. NATIONAL AGENCY-CHECK. —A national agency check (NAC) is a check of federal agency files on persons who apply for employment by federal agencies. The check, conducted by DIS, includes a check of the Defense Central Index of Investigations (DCII) and a check of FBI files. An NAC includes a check on other agencies when the information on the applicant’s investigative forms indicates a need for one. The NAC conducted on a first-term enlistee in the Navy or  Marine  Corps  is  called  an  entrance  NAC (ENTNAC). The primary reason for an ENTNAC is to determine a person’s suitability for entry into the service. It is requested only at the time of initial entry, not at reenlistment or at a later date. An NAC is also required for each person accepting a commission in the naval service or a Reserve component commissioned officer status. The NAC is an integral part of each background investigation (BI), special BI (SBI), or periodic reinvestigation  (PR).  When  an  NAC  discloses information that DIS must investigate further to resolve, the result is called an expanded NAC (ENAC). NATIONAL AGENCY CHECK AND IN- QUIRY. —A national agency check and inquiry (NACI) is a check of the files of civilian applicants for employment by federal agencies (an NAC), which  includes  written  inquiries  about  the applicants. The Office of Personnel Management (OPM) conducts this check. It sends inquiries, covering  the  person’s  last  5  years  before application, to law enforcement agencies, former employers, supervisors, references, and schools. DOD NATIONAL AGENCY CHECK PLUS WRITTEN  INQUIRIES.  —A DOD national agency check plus written inquiries (DNACI), conducted by DIS, consists of an NAC, credit 9-41