This reminds me of an incident I saw on television years ago. This couple noticed that they weren't getting their packages and were getting less mail than before. So, they set up a camera. At first, they saw the mailman pass by dropping off the mail. They waited eagerly to see who would come by later to steal the mail. What do they see? The same mailman driving by again and taking the mail back out.
There was another incident with Netflix and Blockbuster Online. There was a large number of customers not getting their DVDs mailed to them or returned. Upon investigation, they determined the location and caught the mailman collecting those DVDs in a trash bag. He would "throw it away" during work hours, then come back to the trash to pick it up after work. They followed him and caught him.