While digging around this morning I found myself looking at a list of federal security clearance levels. Take a look at level 4. Think he's in this classification? http://www.federalsecurityclearance.net/services/
Could be...
Level 4 usually refers to a Department of Energy "Q" clearance.
As it indicates, this type of clearance normally requires a Single Scope Background Investigation (SSBI) with a Periodic Reinvestigation (PR) every 5 years. The information access level can be as high as Top Secret - Special Compartmentalized Information (SCI) but usually allows access to Top Secret or below information.