The latter three occupation categories contain the core of USPS total systems understanding. In fact, the classification analysts write the regulations that direct the conduct of the public with respect to the use of the mails.
What little public information the FBI has provided concerning how mail moves, etc., has demonstrated only the most primitive of understandings.
Decades back there wasn't an FBI agent who hadn't paid for his college education by working at least part time in a post office. Today student loans have destroyed that category of FBI employee.
Plus, the Postal Inspection Service has a far higher conviction rate than does the FBI, so there might well be some interagency rivalry in this ~ another form of "compartmentalization" I suppose.
It's not too late to restart the investigation, but this time they should not be so quick to "pursue a theory", but instead they should analyze the devil out of the KNOWN FACTS and how those facts correlate with normal postal operations.
The business of digging up 10,000 residential mail boxes and dragging them off to the old GSA warehouse in Springfield VA need not have happened (for just one example).
Great points. Even though I think the perps are long gone home — Pakistan and North Africa. And dead, namely M. Atta.