We use UPS frequently in business. It could have been as easy as someone knew the documents were being sent, and that person was able to interfere with/bribe a UPS driver when they picked it up from point of origin. The package could still be scanned with location updates along the way, without anyone else realizing it was empty at that point, clear up to actual delivery.
realizing it was empty at that point, clear up to actual delivery.
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it was never delivered, but found in the facility open and empty