- Early evidence of ONI conducting personnel security (background) investigations October 26, 1918
- Investigation by US Civil Service Commission of Persons being employed in National Defense Agencies 19 Jun 1940
- Proposed E.O. entitled _Establishing Interdepartmental Board to Consider Cases of Subversive Activity on the part of Federal Employees_Nov 19,1942
- Personnel Security Investigations Jan 29 1944
- Personnel Security Investigations May 25 1945
- Security Investigations of Communications Intelligence Personnel – 27 October 1950
- Executive Order 10450 Security Requirements for Government Employment Apr 27 1953 – Eliminated loyalty boards, authorized departments to conduct pre-employment investigations for consultants and civil service employees (with Civil Service Commission approval) for sensitive positions.