Reportedly, NONE of the packages were processed for delivery by the PO.
Assuming that’s accurate, NONE have bar-codes and NONE have tracking numbers.
The ONLY way that the FBI would know to BOLO for a package sent to Biden that was not received and at that time unaccounted for, would be prior knowledge.
Seriously, there are only a few explanations.
They got the guy.
They are communicating with the guy.
They have one of several guys.
Someone with knowledge (a friend or relative) of the guy is talking to them.
IF the CNN package was personally dropped off at the mailroom INSIDE the building, they must have ID’d somebody using the surveillance footage from the mailroom cameras.