bureau  checks,  and  written  inquiries  to  current and  former  employers  covering  a  5-year  period. BACKGROUND  INVESTIGATION.  —DIS conducts  a  background  investigation  (BI)  to gather   information   on   a   person’s   loyalty, character,   emotional   stability,   and   reliability. It  consists  of  an  NAC  plus  a  field  investigation consisting of an interview and a written inquiry. Standard BI elements include checks of employ- ment;  education;  organization  affiliations;  local agencies; where the subject has lived, worked, or gone to school; and interviews with persons who know the individual. Depending on the informa- tion disclosed, the BI may also include credit and neighborhood  checks  and  an  interview  of  the subject to resolve any questionable or derogatory information.  The  scope  of  a  BI  usually  covers  a period that extends back 5 years or begins at the 18th  birthday,  whichever  is  the  shorter  period; however, at least the last 2 years are covered, with the exception that no investigation is conducted before  a  person’s  16th  birthday.  No  time  limit is   set   for   the   resolution   of   questionable   or derogatory  information.  The  scope  of  a  BI  for persons  assigned  to  NATO  billets  and  for non-U. S. citizens is 10 years (with the restriction on investigation before the 16th birthday). A full field investigation (FFI) conducted by the FBI or OPM  is  the  equivalent  of  a  BI. SPECIAL   BACKGROUND   INVESTIGA- TION.  —A  special  background  investigation (SBI), conducted by DIS, extends coverage of the person’s  background  to  provide  a  greater  depth of knowledge than a standard BI. An SBI includes an  NAC  on  the  member’s  spouse  or  cohabitant. It also includes an NAC on any immediate family members  18  years  of  age  or  older  who  are  U.S. citizens other than by birth or who are not U.S. citizens. The scope of an SBI covers a period that extends  back  15  years  or  begins  at  the  18th birthday,  whichever  is  the  shorter  period; however, at least the last 2 years are covered, with the exception that no investigation is conducted before  the  person’s  16  birthday.  At  the  present time,  CNO  authorizes  SBIs  only  on  personnel  who have  access  to  certain  information  or  who  are assigned   to   certain   duties.   The   following assignments presently require an SBI: Assignments  requiring  access  to  single  inte- grated operational plan—extremely sensitive information    (SIOP-ESI) Assignments   requiring   access   to   sensitive compartmented   information   (SCI) Assignment  to  Presidential  support  duties Assignment to investigative agencies as special agents   or   investigative   support   personnel requiring  continuous  access  to  investigate  files and materials PERIODIC REINVESTIGATION. —A periodic reinvestigation  (PR)  updates  a  valid  investigation conducted  by  DIS.  It  consists  of  a  personal interview,  an  NAC,  local  checks,  credit  checks, and interviews with employment references and character  references.  A  periodic  reinvestigation also includes a command review of all available records  when  warranted  by  the  facts  of  the case. SPECIAL INVESTIGATIVE INQUIRY.  —A special  investigative  inquiry  (SII),  conducted  by DIS,  has  two  purposes.  The  first  purpose  is  to prove or disprove allegations about a person on whom a personnel security determination has been made. The second is to assess the current eligibility of an individual on whom an unfavorable person- nel  security  determination  had  previously  been made.  An  SII  consists  of  a  limited  inquiry,  a post-judicatory   investigation,   or   some   other type   of   DIS   inquiry.   SIIs   do   not   investigate current criminal activity, sabotage, espionage, or subversion.  The  Naval  Security  and  Investigative Command  investigates  those  matters. Since SIIs supplement the basic PSI, they are not entered as investigations on the Certificate of Personnel  Security  Investigation  Clearance  and Access   (OPNAV   Form   5520/20). The Nuclear Weapons Personnel Reliability  Program Investigative  requirements  for  the  Nuclear Weapons  Personnel  Reliability  Program  (PRP) are  based  on  the  sensitivity  of  the  position occupied. The position may or may not reflect the classification  level  of  information  to  which  the person may have access. Positions in the PRP are designated  as  Critical  or  Controlled. A Critical position in the PRP requires a BI within  the  past  5  years  before  initial  assignment. Continued  assignment  to  a  PRP  position  is allowed without an update of the investigation. 9-42