Which Personnel Security Investigation (PSI) type is required for Sensitive Compartmented Information (SCI) determinations?

The Single Scope Background Investigation (SSBI) is the required Personnel Security Investigation (PSI) type for Sensitive Compartmented Information (SCI) determinations because it is the most comprehensive form of investigation available under the current security clearance program. An SSBI involves an extensive review of a person's background, including their employment history, education, criminal history, financial records, and personal references, as well as interviews with family members, friends, and associates to assess the individual’s loyalty, trustworthiness, and reliability.

The depth of information collected in an SSBI is necessary to ensure that individuals who are granted access to SCI can be reliably trusted not only with sensitive information but also that they do not pose a security threat. This is crucial in national security contexts where the potential risks of unauthorized disclosure are vastly amplified due to the nature of the information involved.

Other investigation types, such as the Access National Agency Check with Inquiries (ANACI) and the Basic Background Investigation (BBI), while important for different levels of security clearances, do not provide the same level of thoroughness required for SCI access. Periodic Reinvestigation (PR) occurs at set intervals after a clearance has already been granted but does not apply as a prerequisite for initial access